condition mean min max ZT0-3 18.359201666666667 9.560955 24.98655 ZT4-7 10.9887 10.9887 10.9887 ZT8-11 12.15685 12.15685 12.15685 ZT12-15 15.261500000000002 12.156500000000001 18.366500000000002 ZT16-19 19.882550000000002 19.882550000000002 19.882550000000002 ZT20-23 23.4331 23.4331 23.4331