pre_text: ( c ) includes the effects of items not considered in the assessment of the operating performance of our business segments which increased operating profit by $ 230 million , $ 150 million after tax ( $ 0.34 per share ) . also includes expenses of $ 16 million , $ 11 million after tax ( $ 0.03 per share ) for a debt exchange , and a reduction in income tax expense of $ 62 million ( $ 0.14 per share ) resulting from a tax benefit related to claims we filed for additional extraterritorial income exclusion ( eti ) tax benefits . on a combined basis , these items increased earnings by $ 201 million after tax ( $ 0.45 per share ) . ( d ) includes the effects of items not considered in the assessment of the operating performance of our business segments which , on a combined basis , increased operating profit by $ 173 million , $ 113 million after tax ( $ 0.25 per share ) . ( e ) includes the effects of items not considered in the assessment of the operating performance of our business segments which decreased operating profit by $ 61 million , $ 54 million after tax ( $ 0.12 per share ) . also includes a charge of $ 154 million , $ 100 million after tax ( $ 0.22 per share ) for the early repayment of debt , and a reduction in income tax expense resulting from the closure of an internal revenue service examination of $ 144 million ( $ 0.32 per share ) . on a combined basis , these items reduced earnings by $ 10 million after tax ( $ 0.02 per share ) . ( f ) includes the effects of items not considered in the assessment of the operating performance of our business segments which , on a combined basis , decreased operating profit by $ 7 million , $ 6 million after tax ( $ 0.01 per share ) . also includes a charge of $ 146 million , $ 96 million after tax ( $ 0.21 per share ) for the early repayment of debt . ( g ) we define return on invested capital ( roic ) as net earnings plus after-tax interest expense divided by average invested capital ( stockholders 2019 equity plus debt ) , after adjusting stockholders 2019 equity by adding back adjustments related to postretirement benefit plans . we believe that reporting roic provides investors with greater visibility into how effectively we use the capital invested in our operations . we use roic to evaluate multi-year investment decisions and as a long-term performance measure , and also use it as a factor in evaluating management performance under certain of our incentive compensation plans . roic is not a measure of financial performance under generally accepted accounting principles , and may not be defined and calculated by other companies in the same manner . roic should not be considered in isolation or as an alternative to net earnings as an indicator of performance . we calculate roic as follows : ( in millions ) 2007 2006 2005 2004 2003 .
post_text: 1 represents after-tax interest expense utilizing the federal statutory rate of 35% ( 35 % ) . 2 debt consists of long-term debt , including current maturities of long-term debt , and short-term borrowings ( if any ) . 3 equity includes non-cash adjustments , primarily for unrecognized benefit plan actuarial losses and prior service costs in 2007 and 2006 , the adjustment for the adoption of fas 158 in 2006 , and the additional minimum pension liability in years prior to 2007 . 4 average benefit plan adjustments reflect the cumulative value of entries identified in our statement of stockholders equity under the captions 201cpostretirement benefit plans , 201d 201cadjustment for adoption of fas 158 201d and 201cminimum pension liability . 201d the total of annual benefit plan adjustments to equity were : 2007 = $ 1706 million ; 2006 = ( $ 1883 ) million ; 2005 = ( $ 105 ) million ; 2004 = ( $ 285 ) million ; 2003 = $ 331 million ; 2002 = ( $ 1537 million ) ; and 2001 = ( $ 33 million ) . as these entries are recorded in the fourth quarter , the value added back to our average equity in a given year is the cumulative impact of all prior year entries plus 20% ( 20 % ) of the current year entry value . 5 yearly averages are calculated using balances at the start of the year and at the end of each quarter. .
table: <i>(In millions)</i> 2007 2006 2005 2004 2003
table: Net earnings $3,033 $2,529 $1,825 $1,266 $1,053
table: Interest expense (multiplied by 65%)<sup>1</sup> 229 235 241 276 317
table: Return $3,262 $2,764 $2,066 $1,542 $1,370
table: Average debt<sup>2, 5</sup> $4,416 $4,727 $5,077 $5,932 $6,612
table: Average equity<sup>3, 5</sup> 7,661 7,686 7,590 7,015 6,170
table: Average benefit plan adjustments<sup>3, 4, 5</sup> 3,171 2,006 1,545 1,296 1,504
table: Average invested capital $15,248 $14,419 $14,212 $14,243 $14,286
table: Return on invested capital 21.4% 19.2% 14.5% 10.8% 9.6%
question: Analyse this data from a financial earnings document. what was the difference in return on invested capital from 2006 to 2007?