compensation cost is generally recognized over the stated vesting period consistent with the terms of the arrangement ( i.e. , either on a straight-line or graded-vesting basis ) . expense recognition is accelerated for retirement-eligible individuals who would meet the requirements for vesting of awards upon their retirement . as of 30 september 2018 , there was no unrecognized compensation cost as all stock option awards were fully vested . cash received from option exercises during fiscal year 2018 was $ 76.2 . the total tax benefit realized from stock option exercises in fiscal year 2018 was $ 25.8 , of which $ 19.0 was the excess tax benefit . restricted stock the grant-date fair value of restricted stock is estimated on the date of grant based on the closing price of the stock , and compensation cost is generally amortized to expense on a straight-line basis over the vesting period during which employees perform related services . expense recognition is accelerated for retirement-eligible individuals who would meet the requirements for vesting of awards upon their retirement . we have elected to account for forfeitures as they occur , rather than to estimate them . forfeitures have not been significant historically . we have issued shares of restricted stock to certain officers . participants are entitled to cash dividends and to vote their respective shares . restrictions on shares lift in one to four years or upon the earlier of retirement , death , or disability . the shares are nontransferable while subject to forfeiture . a summary of restricted stock activity is presented below : restricted stock shares ( 000 ) weighted average grant- date fair value .
what was the decrease observed in the total fair value of restricted stock that vested during 2017 and 2018?
as of 30 september 2018 , there was $ .1 of unrecognized compensation cost related to restricted stock awards . the cost is expected to be recognized over a weighted average period of 0.5 years . the total fair value of restricted stock vested during fiscal years 2018 , 2017 , and 2016 was $ 2.2 , $ 4.1 , and $ 4.3 , respectively . as discussed in note 3 , discontinued operations , air products completed the spin-off of versum on 1 october 2016 . in connection with the spin-off , the company adjusted the number of deferred stock units and stock options pursuant to existing anti-dilution provisions in the ltip to preserve the intrinsic value of the awards immediately before and after the separation . the outstanding awards will continue to vest over the original vesting period defined at the grant date . outstanding awards at the time of spin-off were primarily converted into awards of the holders' employer following the separation . stock awards held upon separation were adjusted based upon the conversion ratio of air products' new york stock exchange ( 201cnyse 201d ) volume weighted-average closing stock price on 30 september 2016 ( $ 150.35 ) to the nyse volume weighted-average opening stock price on 3 october 2016 ( $ 140.38 ) , or 1.071 . the adjustment to the awards did not result in incremental fair value , and no incremental compensation expense was recorded related to the conversion of these awards. .