condition mean min max ZT0-3 2.2277633333333333 1.7269899999999998 2.51541 ZT4-7 3.8478899999999996 3.8478899999999996 3.8478899999999996 ZT8-11 3.772825 3.772825 3.772825 ZT12-15 7.0538375 6.637765 7.4699100000000005 ZT16-19 4.030215 4.030215 4.030215 ZT20-23 3.44156 3.44156 3.44156