condition mean min max ZT0-3 5.789016666666667 5.4612300000000005 6.165375 ZT4-7 8.593074999999999 8.593074999999999 8.593074999999999 ZT8-11 8.10926 8.10926 8.10926 ZT12-15 9.4460075 9.26119 9.630825 ZT16-19 7.64148 7.64148 7.64148 ZT20-23 8.41539 8.41539 8.41539