condition mean min max ZT0-3 1.3994816666666667 1.36775 1.461605 ZT4-7 1.065985 1.065985 1.065985 ZT8-11 1.89562 1.89562 1.89562 ZT12-15 1.3258975 1.290125 1.36167 ZT16-19 1.4392749999999999 1.4392749999999999 1.4392749999999999 ZT20-23 1.5120900000000002 1.5120900000000002 1.5120900000000002