condition mean min max ZT0-3 13.090945 8.335584999999998 17.7081 ZT4-7 9.894245000000002 9.894245000000002 9.894245000000002 ZT8-11 2.641465 2.641465 2.641465 ZT12-15 3.632695 3.2551550000000002 4.010235 ZT16-19 3.23833 3.23833 3.23833 ZT20-23 6.326465 6.326465 6.326465