condition mean min max ZT0-3 1.7952110000000001 1.7952110000000001 1.7952110000000001 ZT4-7 2.649175 2.649175 2.649175 ZT8-11 2.0395936666666667 2.0395936666666667 2.0395936666666667 ZT12-15 1.343025 1.343025 1.343025 ZT16-19 2.6598289999999998 2.6598289999999998 2.6598289999999998 ZT20-23 4.690833 4.690833 4.690833