human
in 2017, the company granted 440076 shares of restricted class a common stock and 7568 shares of restricted stock units. restricted common stock and restricted stock units generally have a vesting period of two to four years. the fair value related to these grants was $58.7 million, which is recognized as compensation expense on an accelerated basis over the vesting period. dividends are accrued on restricted class a common stock and restricted stock units and are paid once the restricted stock vests. in 2017, the company also granted 203298 performance shares. the fair value related to these grants was $25.3 million, which is recognized as compensation expense on an accelerated and straight-lined basis over the vesting period. the vesting of these shares is contingent on meeting stated performance or market conditions. the following table summarizes restricted stock, restricted stock units, and performance shares activity for 2017: number of shares weighted average grant date fair value.
|  | Number of Shares | WeightedAverageGrant DateFair Value |
| --------- | --------- | --------- |
| Outstanding at December 31, 2016 | 1,820,578 | $98 |
| Granted | 650,942 | 129 |
| Vested | (510,590) | 87 |
| Cancelled | (401,699) | 95 |
| Outstanding at December 31, 2017 | 1,559,231 | 116 |
the total fair value of restricted stock, restricted stock units, and performance shares that vested during 2017, 2016 and 2015 was $66.0 million, $59.8 million and $43.3 million, respectively. under the espp, eligible employees may acquire shares of class a common stock using after-tax payroll deductions made during consecutive offering periods of approximately six months in duration. shares are purchased at the end of each offering period at a price of 90% (90%) of the closing price of the class a common stock as reported on the nasdaq global select market. compensation expense is recognized on the dates of purchase for the discount from the closing price. in 2017, 2016 and 2015, a total of 19936, 19858 and 19756 shares, respectively, of class a common stock were issued to participating employees. these shares are subject to a six-month holding period. annual expense of $0.3 million for the purchase discount was recognized in 2017, and $0.2 million was recognized in both 2016 and 2015. non-executive directors receive an annual award of class a common stock with a value equal to $100000. non-executive directors may also elect to receive some or all of the cash portion of their annual stipend, up to $60000, in shares of stock based on the closing price at the date of distribution. as a result, 19736 shares, 26439 shares and 25853 shares of class a common stock were issued to non-executive directors during 2017, 2016 and 2015, respectively. these shares are not subject to any vesting restrictions. expense of $2.5 million, $2.4 million and $2.5 million related to these stock-based payments was recognized for the years ended december 31, 2017, 2016 and 2015, respectively. .
Please compute the result.
what is the total purchase discount for 2017 and 2016?
assistant
0.5
human
what about the total if 2015 is included?
assistant
0.7