condition mean min max ZT0-3 1.8044816666666668 1.634645 2.129045 ZT4-7 1.405581 1.405581 1.405581 ZT8-11 2.0223199999999997 2.0223199999999997 2.0223199999999997 ZT12-15 5.9860275 5.55068 6.421374999999999 ZT16-19 5.831255 5.831255 5.831255 ZT20-23 3.72283 3.72283 3.72283