united parcel service , inc . and subsidiaries notes to consolidated financial statements capital lease obligations we have certain property , plant and equipment subject to capital leases . some of the obligations associated with these capital leases have been legally defeased . the recorded value of our property , plant and equipment subject to capital leases is as follows as of december 31 ( in millions ) : .
what was the change in millions of aircraft from 2014 to 2015?
these capital lease obligations have principal payments due at various dates from 2016 through 3005 . facility notes and bonds we have entered into agreements with certain municipalities to finance the construction of , or improvements to , facilities that support our u.s . domestic package and supply chain & freight operations in the united states . these facilities are located around airport properties in louisville , kentucky ; dallas , texas ; and philadelphia , pennsylvania . under these arrangements , we enter into a lease or loan agreement that covers the debt service obligations on the bonds issued by the municipalities , as follows : 2022 bonds with a principal balance of $ 149 million issued by the louisville regional airport authority associated with our worldport facility in louisville , kentucky . the bonds , which are due in january 2029 , bear interest at a variable rate , and the average interest rates for 2015 and 2014 were 0.03% ( 0.03 % ) and 0.05% ( 0.05 % ) , respectively . 2022 bonds with a principal balance of $ 42 million and due in november 2036 issued by the louisville regional airport authority associated with our air freight facility in louisville , kentucky . the bonds bear interest at a variable rate , and the average interest rates for 2015 and 2014 were 0.02% ( 0.02 % ) and 0.05% ( 0.05 % ) , respectively . 2022 bonds with a principal balance of $ 29 million issued by the dallas / fort worth international airport facility improvement corporation associated with our dallas , texas airport facilities . the bonds are due in may 2032 and bear interest at a variable rate , however the variable cash flows on the obligation have been swapped to a fixed 5.11% ( 5.11 % ) . 2022 bonds with a principal balance of $ 100 million issued by the delaware county , pennsylvania industrial development authority associated with our philadelphia , pennsylvania airport facilities . the bonds , which were due in december 2015 , had a variable interest rate , and the average interest rates for 2015 and 2014 were 0.02% ( 0.02 % ) and 0.04% ( 0.04 % ) , respectively . as of december 2015 , these $ 100 million bonds were repaid in full . 2022 in september 2015 , we entered into an agreement with the delaware county , pennsylvania industrial development authority , associated with our philadelphia , pennsylvania airport facilities , for bonds issued with a principal balance of $ 100 million . these bonds , which are due september 2045 , bear interest at a variable rate . the average interest rate for 2015 was 0.00% ( 0.00 % ) . pound sterling notes the pound sterling notes consist of two separate tranches , as follows : 2022 notes with a principal amount of a366 million accrue interest at a 5.50% ( 5.50 % ) fixed rate , and are due in february 2031 . these notes are not callable . 2022 notes with a principal amount of a3455 million accrue interest at a 5.125% ( 5.125 % ) fixed rate , and are due in february 2050 . these notes are callable at our option at a redemption price equal to the greater of 100% ( 100 % ) of the principal amount and accrued interest , or the sum of the present values of the remaining scheduled payout of principal and interest thereon discounted to the date of redemption at a benchmark u.k . government bond yield plus 15 basis points and accrued interest. .