Please answer the given financial question based on the context.
Context: lkq corporation and subsidiaries notes to consolidated financial statements ( continued ) note 5 . long-term obligations ( continued ) as part of the consideration for business acquisitions completed during 2007 , 2006 and 2005 , we issued promissory notes totaling approximately $ 1.7 million , $ 7.2 million and $ 6.4 million , respectively . the notes bear interest at annual rates of 3.0% ( 3.0 % ) to 6.0% ( 6.0 % ) , and interest is payable at maturity or in monthly installments . we also assumed certain liabilities in connection with a business acquisition during the second quarter of 2005 , including a promissory note with a remaining principle balance of approximately $ 0.2 million . the annual interest rate on the note , which was retired during 2006 , was note 6 . commitments and contingencies operating leases we are obligated under noncancelable operating leases for corporate office space , warehouse and distribution facilities , trucks and certain equipment . the future minimum lease commitments under these leases at december 31 , 2007 are as follows ( in thousands ) : years ending december 31: .
|2008|$ 42335|
|2009|33249|
|2010|25149|
|2011|17425|
|2012|11750|
|thereafter|28581|
|future minimum lease payments|$ 158489|
rental expense for operating leases was approximately $ 27.4 million , $ 18.6 million and $ 12.2 million during the years ended december 31 , 2007 , 2006 and 2005 , respectively . we guaranty the residual values of the majority of our truck and equipment operating leases . the residual values decline over the lease terms to a defined percentage of original cost . in the event the lessor does not realize the residual value when a piece of equipment is sold , we would be responsible for a portion of the shortfall . similarly , if the lessor realizes more than the residual value when a piece of equipment is sold , we would be paid the amount realized over the residual value . had we terminated all of our operating leases subject to these guaranties at december 31 , 2007 , the guarantied residual value would have totaled approximately $ 24.0 million . litigation and related contingencies on december 2 , 2005 , ford global technologies , llc ( 2018 2018ford 2019 2019 ) filed a complaint with the united states international trade commission ( 2018 2018usitc 2019 2019 ) against keystone and five other named respondents , including four taiwan-based manufacturers . on december 12 , 2005 , ford filed an amended complaint . both the complaint and the amended complaint contended that keystone and the other respondents infringed 14 design patents that ford alleges cover eight parts on the 2004-2005 .
Question: what was the percentage change in rental expense from 2006 to 2007?


Answer: The answer is:0.47312