condition mean min max ZT0-3 6.322886666666667 4.847535 7.621550000000001 ZT4-7 4.6024449999999995 4.6024449999999995 4.6024449999999995 ZT8-11 5.316330000000001 5.316330000000001 5.316330000000001 ZT12-15 7.9113750000000005 7.63219 8.190560000000001 ZT16-19 6.8738399999999995 6.8738399999999995 6.8738399999999995 ZT20-23 8.017925 8.017925 8.017925