[["", "shares ( in thousands )", "weighted-averagegrant-datefair value"], ["unvested at may 31 2015", "1848", "$ 28.97"], ["granted", "461", "57.04"], ["vested", "-633 ( 633 )", "27.55"], ["forfeited", "-70 ( 70 )", "34.69"], ["unvested at may 31 2016", "1606", "37.25"], ["granted", "348", "74.26"], ["vested", "-639 ( 639 )", "31.38"], ["forfeited", "-52 ( 52 )", "45.27"], ["unvested at december 31 2016", "1263", "49.55"], ["granted", "899", "79.79"], ["vested", "-858 ( 858 )", "39