condition mean min max ZT0-3 3.021866666666667 2.601085 3.5201700000000002 ZT4-7 0.8120645 0.8120645 0.8120645 ZT8-11 0.3790975 0.3790975 0.3790975 ZT12-15 0.59637125 0.5198309999999999 0.6729115 ZT16-19 0.547837 0.547837 0.547837 ZT20-23 1.268775 1.268775 1.268775