supplies . expenses for purchased services increased 10% ( 10 % ) compared to 2012 due to logistics management fees , an increase in locomotive overhauls and repairs on jointly owned property . expenses for contract services increased $ 103 million in 2012 versus 2011 , primarily due to increased demand for transportation services purchased by our logistics subsidiaries for their customers and additional costs for repair and maintenance of locomotives and freight cars . depreciation 2013 the majority of depreciation relates to road property , including rail , ties , ballast , and other track material . depreciation was up 1% ( 1 % ) compared to 2012 . recent depreciation studies allowed us to use longer estimated service lives for certain equipment , which partially offset the impact of a higher depreciable asset base resulting from larger capital spending in recent years . a higher depreciable asset base , reflecting ongoing capital spending , increased depreciation expense in 2012 compared to 2011 . equipment and other rents 2013 equipment and other rents expense primarily includes rental expense that the railroad pays for freight cars owned by other railroads or private companies ; freight car , intermodal , and locomotive leases ; and office and other rent expenses . additional container costs resulting from the logistics management arrangement , and increased automotive shipments , partially offset by lower cycle times drove a $ 51 million increase in our short-term freight car rental expense versus 2012 . conversely , lower locomotive and freight car lease expenses partially offset the higher freight car rental expense . increased automotive and intermodal shipments , partially offset by improved car-cycle times , drove an increase in our short-term freight car rental expense in 2012 compared to 2011 . conversely , lower locomotive lease expense partially offset the higher freight car rental expense . other 2013 other expenses include state and local taxes , freight , equipment and property damage , utilities , insurance , personal injury , environmental , employee travel , telephone and cellular , computer software , bad debt , and other general expenses . higher property taxes and costs associated with damaged freight and property increased other costs in 2013 compared to 2012 . continued improvement in our safety performance and lower estimated liability for personal injury , which reduced our personal injury expense year-over-year , partially offset increases in other costs . other costs in 2012 were slightly higher than 2011 primarily due to higher property taxes . despite continual improvement in our safety experience and lower estimated annual costs , personal injury expense increased in 2012 compared to 2011 , as the liability reduction resulting from historical claim experience was less than the reduction in 2011 . non-operating items millions 2013 2012 2011 % (  % ) change 2013 v 2012 % (  % ) change 2012 v 2011 .
what was the average other income from 2011 to 2013
other income 2013 other income increased in 2013 versus 2012 due to higher gains from real estate sales and increased lease income , including the favorable impact from the $ 17 million settlement of a land lease contract . these increases were partially offset by interest received from a tax refund in 2012 . other income decreased in 2012 versus 2011 due to lower gains from real estate sales and higher environmental costs associated with non-operating properties , partially offset by interest received from a tax refund . interest expense 2013 interest expense decreased in 2013 versus 2012 due to a lower effective interest rate of 5.7% ( 5.7 % ) in 2013 versus 6.0% ( 6.0 % ) in 2012 . the increase in the weighted-average debt level to $ 9.6 billion in 2013 from $ 9.1 billion in 2012 partially offset the impact of the lower effective interest rate . interest expense decreased in 2012 versus 2011 reflecting a lower effective interest rate in 2012 of 6.0% ( 6.0 % ) versus 6.2% ( 6.2 % ) in 2011 as the debt level did not materially change from 2011 to 2012. .