Item 2. Properties

Real Estate Portfolio_._ As of December 31, 2017, the Company had interests in 493 shopping center properties aggregating 83.2 million square feet of GLA located in 29 states, Puerto Rico and Canada. In addition, the Company had 372 other property interests, primarily through the Company’s preferred equity investments and other real estate investments, totaling 5.8 million square feet of GLA. The Company’s portfolio is used by its single reportable segment. Open-air shopping centers comprise the primary focus of the Company's current portfolio. As of December 31, 2017, the Company’s Combined Shopping Center Portfolio, including noncontrolling interests, was 96.0% leased.

The Company's open-air shopping center properties, which are generally owned and operated through subsidiaries or joint ventures, had an average size of 168,433 square feet as of December 31, 2017. The Company generally retains its shopping centers for long-term investment and consequently pursues a program of regular physical maintenance together with redevelopment, major renovations and refurbishing to preserve and increase the value of its properties. This includes renovating existing facades, installing uniform signage, resurfacing parking lots and enhancing parking lot lighting. During 2017, the Company expended $206.8 million in connection with these property improvements and expensed to operations $32.6 million.

The Company's management believes its experience in the real estate industry and its relationships with numerous national and regional tenants gives it an advantage in an industry where ownership is fragmented among a large number of property owners. The Company's open-air shopping centers are usually "anchored" by a grocery store, national or regional discount department store or drugstore. As one of the original participants in the growth of the shopping center industry and one of the nation's largest owners and operators of shopping centers, the Company has established close relationships with a large number of major national and regional retailers. Some of the major national and regional companies that are tenants in the Company's shopping center properties include TJX Companies, The Home Depot, Ahold Delhaize, Bed Bath & Beyond, Albertsons, Ross Stores, Petsmart, Kohl’s, Wal-Mart and Whole Foods.

The Company reduces its operating and leasing risks through diversification achieved by the geographic distribution of its properties and a large tenant base. As of December 31, 2017, no single open-air shopping center accounted for more than 1.8% of the Company's annualized base rental revenues, including the proportionate share of base rental revenues from properties in which the Company has less than a 100% economic interest, or more than 1.6% of the Company’s total shopping center GLA. At December 31, 2017, the Company’s five largest tenants were TJX Companies, The Home Depot, Ahold Delhaize, Bed Bath & Beyond and Albertsons, which represented 3.6%, 2.5%, 2.2%, 1.8% and 1.8%, respectively, of the Company’s annualized base rental revenues, including the proportionate share of base rental revenues from properties in which the Company has less than a 100% economic interest.

A substantial portion of the Company's income consists of rent received under long-term leases. Most of the leases provide for the payment of fixed-base rentals monthly in advance and for the payment by tenants of an allocable share of the real estate taxes, insurance, utilities and common area maintenance expenses incurred in operating the shopping centers. Although many of the leases require the Company to make roof and structural repairs as needed, a number of tenant leases place that responsibility on the tenant, and the Company's standard small store lease provides for reimbursements by the tenant as part of common area maintenance.

Minimum base rental revenues and operating expense reimbursements accounted for 97% and other revenues, including percentage rents, accounted for 3% of the Company's total revenues from rental properties for the year ended December 31, 2017. The Company's management believes that the base rent per leased square foot for many of the Company's existing leases is generally lower than the prevailing market-rate base rents in the geographic regions where the Company operates, reflecting the potential for future growth. Additionally, a majority of the Company’s leases have provisions requiring contractual rent increases. The Company’s leases may also include escalation clauses, which provide for increases based upon changes in the consumer price index or similar inflation indices.

As of December 31, 2017, the Company’s consolidated operating portfolio, comprised of 59.4 million square feet of GLA, was 95.9% leased. The consolidated operating portfolio consists entirely of properties located in the U.S., inclusive of Puerto Rico. For the period January 1, 2017 to December 31, 2017, the Company increased the average base rent per leased square foot, which includes the impact of tenant concessions, in its consolidated portfolio of open-air shopping centers from $14.99 to $15.43, an increase of $0.44. This increase primarily consists of (i) a $0.30 increase relating to new leases signed net of leases vacated and rent step-ups within the portfolio, (ii) a $0.13 increase relating to dispositions and (iii) a $0.01 increase relating to acquisitions.

The Company has a total of 6,089 leases in the U.S. consolidated operating portfolio. The following table sets forth the aggregate lease expirations for each of the next ten years, assuming no renewal options are exercised. For purposes of the table, the Total Annual Base Rent Expiring represents annualized rental revenue, excluding the impact of straight-line rent, for each lease that expires during the respective year. Amounts in thousands except for number of lease data:

During 2017, the Company executed 1,196 leases totaling over 8.9 million square feet in the Company’s consolidated operating portfolio comprised of 451 new leases and 745 renewals and options. The leasing costs associated with these leases are estimated to aggregate $75.7 million or $28.58 per square foot. These costs include $59.3 million of tenant improvements and $16.4 million of leasing commissions. The average rent per square foot on new leases was $18.83 and on renewals and options was $15.86. The Company will seek to obtain rents that are higher than amounts within its expiring leases, however, there are many variables and uncertainties which can significantly affect the leasing market at any time; as such, the Company cannot guarantee that future leases will continue to be signed for rents that are equal to or higher than current amounts.

Ground-Leased Properties. The Company has interests in 43 consolidated shopping center properties that are subject to long-term ground leases where a third party owns and has leased the underlying land to the Company to construct and/or operate a shopping center. The Company pays rent for the use of the land and generally is responsible for all costs and expenses associated with the building and improvements. At the end of these long-term leases, unless extended, the land together with all improvements reverts to the landowner.

More specific information with respect to each of the Company's property interests is set forth in Exhibit 99.1, which is incorporated herein by reference.