to determine stock-based compensation expense , the grant date fair value is applied to the options granted with a reduction for estimated forfeitures . we recognize compensation expense for stock options on a straight-line basis over the specified vesting period . at december 31 , 2013 and 2012 , options for 10204000 and 12759000 shares of common stock were exercisable at a weighted-average price of $ 89.46 and $ 90.86 , respectively . the total intrinsic value of options exercised during 2014 , 2013 and 2012 was $ 90 million , $ 86 million and $ 37 million , respectively . cash received from option exercises under all incentive plans for 2014 , 2013 and 2012 was approximately $ 215 million , $ 208 million and $ 118 million , respectively . the tax benefit realized from option exercises under all incentive plans for 2014 , 2013 and 2012 was approximately $ 33 million , $ 31 million and $ 14 million , respectively . shares of common stock available during the next year for the granting of options and other awards under the incentive plans were 17997353 at december 31 , 2014 . total shares of pnc common stock authorized for future issuance under equity compensation plans totaled 19017057 shares at december 31 , 2014 , which includes shares available for issuance under the incentive plans and the employee stock purchase plan ( espp ) as described below . during 2014 , we issued approximately 2.4 million shares from treasury stock in connection with stock option exercise activity . as with past exercise activity , we currently intend to utilize primarily treasury stock for any future stock option exercises . awards granted to non-employee directors in 2014 , 2013 and 2012 include 21490 , 27076 and 25620 deferred stock units , respectively , awarded under the outside directors deferred stock unit plan . a deferred stock unit is a phantom share of our common stock , which is accounted for as a liability until such awards are paid to the participants in cash . as there are no vesting or service requirements on these awards , total compensation expense is recognized in full for these awards on the date of grant . incentive/performance unit share awards and restricted stock/share unit awards the fair value of nonvested incentive/performance unit share awards and restricted stock/share unit awards is initially determined based on prices not less than the market value of our common stock on the date of grant . the value of certain incentive/performance unit share awards is subsequently remeasured based on the achievement of one or more financial and other performance goals . the personnel and compensation committee ( 201cp&cc 201d ) of the board of directors approves the final award payout with respect to certain incentive/performance unit share awards . these awards have either a three-year or a four-year performance period and are payable in either stock or a combination of stock and cash . restricted stock/share unit awards have various vesting periods generally ranging from 3 years to 5 years . beginning in 2013 , we incorporated several enhanced risk- related performance changes to certain long-term incentive compensation programs . in addition to achieving certain financial performance metrics on both an absolute basis and relative to our peers , final payout amounts will be subject to reduction if pnc fails to meet certain risk-related performance metrics as specified in the award agreements . however , the p&cc has the discretion to waive any or all of this reduction under certain circumstances . the weighted-average grant date fair value of incentive/ performance unit share awards and restricted stock/unit awards granted in 2014 , 2013 and 2012 was $ 80.79 , $ 64.77 and $ 60.68 per share , respectively . the total fair value of incentive/performance unit share and restricted stock/unit awards vested during 2014 , 2013 and 2012 was approximately $ 119 million , $ 63 million and $ 55 million , respectively . we recognize compensation expense for such awards ratably over the corresponding vesting and/or performance periods for each type of program . table 121 : nonvested incentive/performance unit share awards and restricted stock/share unit awards 2013 rollforward shares in thousands nonvested incentive/ performance unit shares weighted- average grant date fair value nonvested restricted stock/ weighted- average grant date fair value .

nonvested incentive/ performance unit shares 1647: granted: 723
vested/released: -513
forfeited: -20
december 31 2014: 1837
weighted-averagegrant datefair value $ 63.49: granted: 79.9
vested/released: 63.64
forfeited: 69.18
december 31 2014: 69.84
nonvested restricted stock/ share units 3483: granted: 1276
vested/released: -962
forfeited: -145
december 31 2014: 3652
weighted-averagegrant datefair value $ 62.70: granted: 81.29
vested/released: 62.32
forfeited: 69.44
december 31 2014: 69.03

the pnc financial services group , inc . 2013 form 10-k 185 .

Questions:
what was the tax benefit realized from option exercises under all incentive plans in 2014, in millions?
and what was it in 2013, also in millions?
what was, then, in millions, the total tax of benefit realized from option exercises under all incentive plans for both years combined?
what was that tax benefit in 2012, in millions?
including, then, 2012, what then becomes that total of tax benefit realized from option exercises under all incentive plans, in millions?
and what is, in millions, the average tax benefit between those three years?

Answers:
33
31
64
14
78
26