condition mean min max ZT0-3 2.815915 2.815915 2.815915 ZT4-7 1.6284 1.6284 1.6284 ZT8-11 2.8974650000000004 2.8974650000000004 2.8974650000000004 ZT12-15 3.10521 3.10521 3.10521 ZT16-19 4.677289999999999 4.677289999999999 4.677289999999999 ZT20-23 3.92457 3.92457 3.92457