condition mean min max ZT0-3 2.670715 2.670715 2.670715 ZT4-7 1.78339 1.78339 1.78339 ZT8-11 2.2826199999999996 2.2826199999999996 2.2826199999999996 ZT12-15 3.505815 3.505815 3.505815 ZT16-19 3.2512350000000003 3.2512350000000003 3.2512350000000003 ZT20-23 2.75238 2.75238 2.75238