condition mean min max ZT0-3 1.8171333333333333 1.5128849999999998 2.064085 ZT4-7 1.51904 1.51904 1.51904 ZT8-11 1.892325 1.892325 1.892325 ZT12-15 2.05043 1.958525 2.142335 ZT16-19 2.334465 2.334465 2.334465 ZT20-23 2.73154 2.73154 2.73154