condition mean min max ZT0-3 163.770518 163.770518 163.770518 ZT4-7 132.660015 132.660015 132.660015 ZT8-11 176.2418365 176.2418365 176.2418365 ZT12-15 228.6843225 228.6843225 228.6843225 ZT16-19 268.8395345 268.8395345 268.8395345 ZT20-23 330.687358 330.687358 330.687358