56 / 57 management 2019s discussion and analysis of financial condition and results of operations junior subordinate deferrable interest debentures in june 2005 , we issued $ 100.0 a0million of trust preferred securities , which are reflected on the balance sheet as junior subordinate deferrable interest debentures . the proceeds were used to repay our revolving credit facility . the $ 100.0 a0million of junior subordi- nate deferrable interest debentures have a 30-year term ending july 2035 . they bear interest at a fixed rate of 5.61% ( 5.61 % ) for the first 10 years ending july 2015 . thereafter , the rate will float at three month libor plus 1.25% ( 1.25 % ) . the securities are redeemable at par . restrictive covenants the terms of the 2011 revolving credit facility and certain of our senior unsecured notes include certain restrictions and covenants which may limit , among other things , our ability to pay dividends ( as discussed below ) , make certain types of investments , incur additional indebtedness , incur liens and enter into negative pledge agreements and the disposition of assets , and which require compliance with financial ratios including our minimum tangible net worth , a maximum ratio of total indebtedness to total asset value , a minimum ratio of ebitda to fixed charges and a maximum ratio of unsecured indebtedness to unencumbered asset value . the dividend restriction referred to above provides that we will not during any time when we are in default , make distributions with respect to common stock or other equity interests , except to enable us to continue to qualify as a reit for federal income tax purposes . as of december a031 , 2011 and 2010 , we were in compli- ance with all such covenants . market rate risk we are exposed to changes in interest rates primarily from our floating rate borrowing arrangements . we use interest rate deriv- ative instruments to manage exposure to interest rate changes . a a0hypothetical 100 a0basis point increase in interest rates along the entire interest rate curve for 2011 and 2010 , would increase our annual interest cost by approximately $ 12.3 a0million and $ 11.0 a0mil- lion and would increase our share of joint venture annual interest cost by approximately $ 4.8 a0million and $ 6.7 a0million , respectively . we recognize all derivatives on the balance sheet at fair value . derivatives that are not hedges must be adjusted to fair value through income . if a derivative is a hedge , depending on the nature of the hedge , changes in the fair value of the derivative will either be offset against the change in fair value of the hedged asset , liability , or firm commitment through earnings , or recognized in other comprehensive income until the hedged item is recognized in earnings . the ineffective portion of a derivative 2019s change in fair value is recognized immediately in earnings . approximately $ 4.8 a0billion of our long- term debt bore interest a0at fixed rates , and therefore the fair value of these instru- ments is affected by changes in the market interest rates . the interest rate on our variable rate debt and joint venture debt as of december a031 , 2011 ranged from libor plus 150 a0basis points to libor plus 350 a0basis points . contractual obligations combined aggregate principal maturities of mortgages and other loans payable , our 2011 revolving credit facility , senior unsecured notes ( net of discount ) , trust preferred securities , our share of joint venture debt , including as- of-right extension options , estimated interest expense ( based on weighted average interest rates for the quarter ) , and our obligations under our capital lease and ground leases , as of december a031 , 2011 are as follows ( in thousands ) : .

Table:
 | 2012 | 2013 | 2014 | 2015 | 2016 | thereafter | total
property mortgages | $ 52443 | $ 568649 | $ 647776 | $ 270382 | $ 556400 | $ 2278190 | $ 4373840
revolving credit facility | 2014 | 2014 | 2014 | 2014 | 350000 | 2014 | 350000
trust preferred securities | 2014 | 2014 | 2014 | 2014 | 2014 | 100000 | 100000
senior unsecured notes | 119423 | 2014 | 98578 | 657 | 274804 | 777194 | 1270656
capital lease | 1555 | 1555 | 1555 | 1592 | 1707 | 42351 | 50315
ground leases | 33429 | 33429 | 33429 | 33429 | 33533 | 615450 | 782699
estimated interest expense | 312672 | 309280 | 269286 | 244709 | 212328 | 470359 | 1818634
joint venture debt | 176457 | 93683 | 123983 | 102476 | 527814 | 800102 | 1824515
total | $ 695979 | $ 1006596 | $ 1174607 | $ 653245 | $ 1956586 | $ 5083646 | $ 10570659
.

Question: a hypothetical 100 basis point increase in interest rates along the entire interest rate curve for 2011 and 2010 would increase our annual interest cost by what average amount , in millions?
Answer: 11.6
Calculation: add(12.3, 11.0), divide(#0, const_2)