condition mean min max ZT0-3 7.681326 7.681326 7.681326 ZT4-7 7.5170025 7.5170025 7.5170025 ZT8-11 7.854744999999999 7.854744999999999 7.854744999999999 ZT12-15 7.2152365 7.2152365 7.2152365 ZT16-19 7.4732425 7.4732425 7.4732425 ZT20-23 7.4004525 7.4004525 7.4004525