compared to 2007 . we reduced personal injury expense by $ 80 million in 2007 as a result of fewer than expected claims and lower than expected average settlement costs . in 2008 , we reduced personal injury expense and asbestos-related costs $ 82 million based on the results of updated personal injury actuarial studies and a reassessment of our potential liability for resolution of current and future asbestos claims . in addition , environmental and toxic tort expenses were $ 7 million lower in 2008 compared to 2007 . other costs were lower in 2007 compared to 2006 driven primarily by a reduction in personal injury expense . actuarial studies completed during 2007 resulted in a reduction in personal injury expense of $ 80 million , which was partially offset by an adverse development with respect to one claim . settlement of insurance claims in 2007 related to hurricane rita , and higher equity income also drove expenses lower in 2007 versus 2006 . conversely , the year-over-year comparison was affected by the settlement of insurance claims totaling $ 23 million in 2006 related to the january 2005 west coast storm and a $ 9 million gain in 2006 from the sale of two company-owned airplanes . non-operating items millions of dollars 2008 2007 2006 % (  % ) change 2008 v 2007 % (  % ) change 2007 v 2006 .

2008: other income: 92
interest expense: -511
income taxes: -1318
2007: other income: 116
interest expense: -482
income taxes: -1154
2006: other income: 118
interest expense: -477
income taxes: -919
% (  % ) change 2008 v 2007: other income: -21
interest expense: 6
income taxes: -14
% (  % ) change 2007 v 2006: other income: -2
interest expense: 1
income taxes: -26

other income 2013 other income decreased in 2008 compared to 2007 due to lower gains from real estate sales and decreased returns on cash investments reflecting lower interest rates . higher rental and licensing income and lower interest expense on our sale of receivables program partially offset the decreases . lower net gains from non-operating asset sales ( primarily real estate ) drove the reduction in other income in 2007 . recognition of rental income in 2006 from the settlement of a rent dispute also contributed to the year-over-year decrease in other income . cash investment returns increased $ 21 million due to larger cash balances and higher interest rates . interest expense 2013 interest expense increased in 2008 versus 2007 due to a higher weighted-average debt level of $ 8.3 billion , compared to $ 7.3 billion in 2007 . a lower effective interest rate of 6.1% ( 6.1 % ) in 2008 , compared to 6.6% ( 6.6 % ) in 2007 , partially offset the effects of the higher weighted-average debt level . an increase in the weighted-average debt levels to $ 7.3 billion from $ 7.1 billion in 2006 generated higher interest expense in 2007 . a lower effective interest rate of 6.6% ( 6.6 % ) in 2007 , compared to 6.7% ( 6.7 % ) in 2006 , partially offset the effects of the higher debt level . income taxes 2013 income taxes were higher in 2008 compared to 2007 , driven by higher pre-tax income . our effective tax rates were 36.1% ( 36.1 % ) and 38.4% ( 38.4 % ) in 2008 and 2007 , respectively . the lower effective tax rate in 2008 resulted from several reductions in tax expense related to federal audits and state tax law changes . in addition , the effective tax rate in 2007 was increased by illinois legislation that increased deferred tax expense in the third quarter of 2007 . income taxes were $ 235 million higher in 2007 compared to 2006 , due primarily to higher pre-tax income and the effect of new tax legislation in the state of illinois that changed how we determine the amount of our income subject to illinois tax . the illinois legislation increased our deferred tax expense by $ 27 million in 2007 . our effective tax rates were 38.4% ( 38.4 % ) and 36.4% ( 36.4 % ) in 2007 and 2006 , respectively. .

Questions:
what was the sum of other income in 2007 and 2008?
what is the total sum including 2006?
what is that divided by 3?

Answers:
208
326
108.7