condition mean min max ZT0-3 1.6310566666666666 1.35266 2.127405 ZT4-7 1.6890550000000002 1.6890550000000002 1.6890550000000002 ZT8-11 2.184715 2.184715 2.184715 ZT12-15 2.1263275 1.8625099999999999 2.390145 ZT16-19 2.03571 2.03571 2.03571 ZT20-23 2.29028 2.29028 2.29028