condition mean min max ZT0-3 4.546103333333333 2.81528 5.6917349999999995 ZT4-7 1.41715 1.41715 1.41715 ZT8-11 2.1014549999999996 2.1014549999999996 2.1014549999999996 ZT12-15 6.489915 4.77028 8.20955 ZT16-19 8.095175 8.095175 8.095175 ZT20-23 8.90646 8.90646 8.90646