condition mean min max ZT0-3 20.6532 19.330849999999998 21.97555 ZT4-7 17.5257 17.5257 17.5257 ZT8-11 20.7239 20.7239 20.7239 ZT12-15 0 0 0 ZT16-19 21.25585 21.25585 21.25585 ZT20-23 22.29405 22.29405 22.29405