9. Notes Payable

The following is a summary of our indebtedness:



	December 31,
(in millions)	2014		2013
Senior unsecured notes
5.08% Notes, due 2015	$	249.9	$	249.7
5.75% Notes, due 2017	246.5		246.4
4.70% Notes, due 2021	249.0		248.8
3.07% Notes, due 2022	347.0		346.7
5.00% Notes, due 2023	247.8		247.7
4.27% Notes, due 2024	249.6		249.5
3.59% Notes, due 2024	248.1		—
	$	1,837.9	$	1,588.8

Secured notes
0.91% – 5.63% Conventional Mortgage Notes, due 2018 – 2045	870.9		905.7
Tax-exempt Mortgage Note, due 2028 (1.30% floating rate)	34.7		36.3
	905.6		942.0
Total notes payable	$	2,743.5	$	2,530.8

Other floating rate debt included in secured notes (0.91%)	$	175.0	$	175.0
Value of real estate assets, at cost, subject to secured notes	$	1,541.3	$	1,582.5

We have a $500 million unsecured credit facility which matures in September 2015 with an option to extend at our election to September 2016. Additionally, we have the option to increase this credit facility to $750 million by either adding additional banks to the credit facility or obtaining the agreement of the existing banks in the credit facility to increase their commitments. The interest rate is based upon the London Interbank Offered Rate ("LIBOR") plus a margin which is subject to change as our credit ratings change. Advances under the line of credit may be priced at the scheduled rates, or we may enter into bid rate loans with participating banks at rates below the scheduled rates. These bid rate loans have terms of 180 days or less and may not exceed the lesser of $250 million or the remaining amount available under the line of credit. The line of credit is subject to customary financial covenants and limitations. We believe we are in compliance with all such financial covenants and limitations on the date of this filing.

Our line of credit provides us with the ability to issue up to $100 million in letters of credit. While our issuance of letters of credit does not increase our borrowings outstanding under our line of credit, it does reduce the amount available. At December 31, 2014, we had no short-term balances outstanding, no balances outstanding on our $500 million unsecured line of credit, and we had outstanding letters of credit totaling approximately $6.4 million, leaving approximately $493.6 million available under our unsecured line of credit.

In September 2014, we issued $250 million aggregate principal amount of 3.50% senior unsecured notes due September 2024 (the “2024 Notes”). The 2024 Notes were offered to the public at 99.231% of their face amount with a stated rate of 3.50% and a yield to maturity of 3.59%. We received net proceeds of approximately $245.7 million, net of underwriting discounts and other offering expenses. Interest on the 2024 Notes is payable semi-annually on March 15 and September 15, beginning March 15, 2015. We may redeem the 2024 Notes, in whole or in part, at any time at a redemption price equal to the principal amount and accrued interest of the notes being redeemed, plus a make-whole provision. If, however, we redeem the 2024 Notes 90 days or fewer prior to the maturity date, the redemption price will equal 100% of the principal amount of the 2024 Notes to be redeemed plus accrued and unpaid interest on the amount being redeemed to the redemption date. The 2024 Notes are direct, senior unsecured obligations and rank equally with all of our other unsecured and unsubordinated indebtedness. We used the proceeds from this offering to repay outstanding balances on our unsecured line of credit and other short-term borrowings, and for general corporate purposes, including property acquisition and development in the ordinary course of business, capital expenditures and working capital.

At December 31, 2014 and 2013, the weighted average interest rate on our floating rate debt of approximately $209.7 million and $211.3 million, respectively, was approximately 1.0% for each of the years ended December 31, 2014 and 2013.

Our indebtedness had a weighted average maturity of 6.3 years at December 31, 2014. Scheduled repayments on outstanding debt and scheduled principal amortizations, and the respective weighted average interest rates on maturing debt at December 31, 2014 were as follows:



(in millions)	Amount		Weighted Average Interest Rate
2015	$	251.8	5.1	%
2016 (1)	2.0		—
2017	249.0		5.7
2018	177.4		0.9
2019	646.5		5.3
Thereafter	1,416.8		4.0
Total	$	2,743.5	4.4	%


(1)	Includes only scheduled principal amortizations.