39 annual report 2010 duke realty corporation | | related party transactions we provide property and asset management , leasing , construction and other tenant related services to unconsolidated companies in which we have equity interests .
for the years ended december 31 , 2010 , 2009 and 2008 , respectively , we earned management fees of $ 7.6 million , $ 8.4 million and $ 7.8 million , leasing fees of $ 2.7 million , $ 4.2 million and $ 2.8 million and construction and development fees of $ 10.3 million , $ 10.2 million and $ 12.7 million from these companies .
we recorded these fees based on contractual terms that approximate market rates for these types of services , and we have eliminated our ownership percentages of these fees in the consolidated financial statements .
commitments and contingencies we have guaranteed the repayment of $ 95.4 million of economic development bonds issued by various municipalities in connection with certain commercial developments .
we will be required to make payments under our guarantees to the extent that incremental taxes from specified developments are not sufficient to pay the bond debt service .
management does not believe that it is probable that we will be required to make any significant payments in satisfaction of these guarantees .
we also have guaranteed the repayment of secured and unsecured loans of six of our unconsolidated subsidiaries .
at december 31 , 2010 , the maximum guarantee exposure for these loans was approximately $ 245.4 million .
with the exception of the guarantee of the debt of 3630 peachtree joint venture , for which we recorded a contingent liability in 2009 of $ 36.3 million , management believes it probable that we will not be required to satisfy these guarantees .
we lease certain land positions with terms extending to december 2080 , with a total obligation of $ 103.6 million .
no payments on these ground leases are material in any individual year .
we are subject to various legal proceedings and claims that arise in the ordinary course of business .
in the opinion of management , the amount of any ultimate liability with respect to these actions will not materially affect our consolidated financial statements or results of operations .
contractual obligations at december 31 , 2010 , we were subject to certain contractual payment obligations as described in the table below: .

contractual obligations
payments due by period ( in thousands ) total
payments due by period ( in thousands ) 2011
payments due by period ( in thousands ) 2012
payments due by period ( in thousands ) 2013
payments due by period ( in thousands ) 2014
payments due by period ( in thousands ) 2015
payments due by period ( in thousands ) thereafter
long-term debt ( 1 )
$ 5413606
$ 629781
$ 548966
$ 725060
$ 498912
$ 473417
$ 2537470
lines of credit ( 2 )
214225
28046
9604
176575
-
-
-
share of debt of unconsolidated joint ventures ( 3 )
447573
87602
27169
93663
34854
65847
138438
ground leases
103563
2199
2198
2169
2192
2202
92603
operating leases
2704
840
419
395
380
370
300
development and construction backlog costs ( 4 )
521041
476314
44727
-
-
-
-
other
1967
1015
398
229
90
54
181
total contractual obligations
$ 6704679
$ 1225797
$ 633481
$ 998091
$ 536428
$ 541890
$ 2768992

( 1 ) our long-term debt consists of both secured and unsecured debt and includes both principal and interest .
interest expense for variable rate debt was calculated using the interest rates as of december 31 , 2010 .
( 2 ) our unsecured lines of credit consist of an operating line of credit that matures february 2013 and the line of credit of a consolidated subsidiary that matures july 2011 .
interest expense for our unsecured lines of credit was calculated using the most recent stated interest rates that were in effect .
( 3 ) our share of unconsolidated joint venture debt includes both principal and interest .
interest expense for variable rate debt was calculated using the interest rate at december 31 , 2010 .
( 4 ) represents estimated remaining costs on the completion of owned development projects and third-party construction projects. .

Question: what is the total long-term debt as a percentage of total contractual obligations?
Answer: 80.7%