condition mean min max ZT0-3 5.682736666666667 2.7900650000000002 7.684089999999999 ZT4-7 3.284655 3.284655 3.284655 ZT8-11 4.304915 4.304915 4.304915 ZT12-15 7.00786 5.303710000000001 8.71201 ZT16-19 11.6811 11.6811 11.6811 ZT20-23 14.1102 14.1102 14.1102