Financial report context:
the environmental liability includes costs for remediation and restoration of sites , as well as for ongoing monitoring costs , but excludes any anticipated recoveries from third parties . cost estimates are based on information available for each site , financial viability of other potentially responsible parties , and existing technology , laws , and regulations . we believe that we have adequately accrued for our ultimate share of costs at sites subject to joint and several liability . however , the ultimate liability for remediation is difficult to determine because of the number of potentially responsible parties involved , site-specific cost sharing arrangements with other potentially responsible parties , the degree of contamination by various wastes , the scarcity and quality of volumetric data related to many of the sites , and the speculative nature of remediation costs . estimates may also vary due to changes in federal , state , and local laws governing environmental remediation . we do not expect current obligations to have a material adverse effect on our results of operations or financial condition . guarantees 2013 at december 31 , 2006 , we were contingently liable for $ 464 million in guarantees . we have recorded a liability of $ 6 million for the fair value of these obligations as of december 31 , 2006 . we entered into these contingent guarantees in the normal course of business , and they include guaranteed obligations related to our headquarters building , equipment financings , and affiliated operations . the final guarantee expires in 2022 . we are not aware of any existing event of default that would require us to satisfy these guarantees . we do not expect that these guarantees will have a material adverse effect on our consolidated financial condition , results of operations , or liquidity . indemnities 2013 our maximum potential exposure under indemnification arrangements , including certain tax indemnifications , can range from a specified dollar amount to an unlimited amount , depending on the nature of the transactions and the agreements . due to uncertainty as to whether claims will be made or how they will be resolved , we cannot reasonably determine the probability of an adverse claim or reasonably estimate any adverse liability or the total maximum exposure under these indemnification arrangements . we do not have any reason to believe that we will be required to make any material payments under these indemnity provisions . income taxes 2013 as previously reported in our form 10-q for the quarter ended september 30 , 2005 , the irs has completed its examinations and issued notices of deficiency for tax years 1995 through 2002 . among their proposed adjustments is the disallowance of tax deductions claimed in connection with certain donations of property . in the fourth quarter of 2005 , the irs national office issued a technical advice memorandum which left unresolved whether the deductions were proper , pending further factual development . we continue to dispute the donation issue , as well as many of the other proposed adjustments , and will contest the associated tax deficiencies through the irs appeals process , and , if necessary , litigation . in addition , the irs is examining the corporation 2019s federal income tax returns for tax years 2003 and 2004 and should complete their exam in 2007 . we do not expect that the ultimate resolution of these examinations will have a material adverse effect on our consolidated financial statements . 11 . other income other income included the following for the years ended december 31 : millions of dollars 2006 2005 2004 .

Financial table:
millions of dollars: rental income; 2006: $ 83; 2005: $ 59; 2004: $ 55
millions of dollars: net gain on non-operating asset dispositions; 2006: 72; 2005: 135; 2004: 69
millions of dollars: interest income; 2006: 29; 2005: 17; 2004: 10
millions of dollars: sale of receivables fees; 2006: -33 ( 33 ); 2005: -23 ( 23 ); 2004: -11 ( 11 )
millions of dollars: non-operating environmental costs and other; 2006: -33 ( 33 ); 2005: -43 ( 43 ); 2004: -35 ( 35 )
millions of dollars: total; 2006: $ 118; 2005: $ 145; 2004: $ 88

Additional report context:
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Question: what was the percentage change in rental income from 2005 to 2006?
Answer: 41%