condition mean min max ZT0-3 1.2517231666666666 0.597075 2.091315 ZT4-7 1.15536 1.15536 1.15536 ZT8-11 1.2685650000000002 1.2685650000000002 1.2685650000000002 ZT12-15 1.3423690000000001 0.509493 2.1752450000000003 ZT16-19 0.7654895 0.7654895 0.7654895 ZT20-23 0.7774385 0.7774385 0.7774385