pre_text: prior to its adoption of sfas no . 123 ( r ) , the company recorded compensation expense for restricted stock awards on a straight-line basis over their vesting period . if an employee forfeited the award prior to vesting , the company reversed out the previously expensed amounts in the period of forfeiture . as required upon adoption of sfas no . 123 ( r ) , the company must base its accruals of compensation expense on the estimated number of awards for which the requisite service period is expected to be rendered . actual forfeitures are no longer recorded in the period of forfeiture . in 2005 , the company recorded a pre-tax credit of $ 2.8 million in cumulative effect of accounting change , that represents the amount by which compensation expense would have been reduced in periods prior to adoption of sfas no . 123 ( r ) for restricted stock awards outstanding on july 1 , 2005 that are anticipated to be forfeited . a summary of non-vested restricted stock award and restricted stock unit activity is presented below : shares ( in thousands ) weighted- average date fair .
post_text: as of december 31 , 2007 , there was $ 15.3 million of total unrecognized compensation cost related to non-vested awards . this cost is expected to be recognized over a weighted-average period of 1.6 years . the total fair value of restricted shares and restricted stock units vested was $ 11.0 million , $ 7.5 million and $ 4.1 million for the years ended december 31 , 2007 , 2006 and 2005 , respectively . employee stock purchase plan the shareholders of the company previously approved the 2002 employee stock purchase plan ( 201c2002 purchase plan 201d ) , and reserved 5000000 shares of common stock for sale to employees at a price no less than 85% ( 85 % ) of the lower of the fair market value of the common stock at the beginning of the one-year offering period or the end of each of the six-month purchase periods . under sfas no . 123 ( r ) , the 2002 purchase plan was considered compensatory . effective august 1 , 2005 , the company changed the terms of its purchase plan to reduce the discount to 5% ( 5 % ) and discontinued the look-back provision . as a result , the purchase plan was not compensatory beginning august 1 , 2005 . for the year ended december 31 , 2005 , the company recorded $ 0.4 million in compensation expense for its employee stock purchase plan for the period in which the 2002 plan was considered compensatory until the terms were changed august 1 , 2005 . at december 31 , 2007 , 757123 shares were available for purchase under the 2002 purchase plan . 401 ( k ) plan the company has a 401 ( k ) salary deferral program for eligible employees who have met certain service requirements . the company matches certain employee contributions ; additional contributions to this plan are at the discretion of the company . total contribution expense under this plan was $ 5.7 million , $ 5.7 million and $ 5.2 million for the years ended december 31 , 2007 , 2006 and 2005 , respectively. .
table: Shares (in thousands) Weighted- Average Grant Date Fair Value
table: Non-vested at December 31, 2006: 2,878 $13.01
table: Issued 830 $22.85
table: Released (vested) (514) $15.93
table: Canceled (1,197) $13.75
table: Non-vested at December 31, 2007: 1,997 $15.91
question: Analyse this data from a financial earnings document. what was the percentage change in total contribution expense under the plan between 2006 and 2007?