condition mean min max ZT0-3 2.7258115607499995 1.7824247574999998 3.6691983639999997 ZT4-7 3.2882296395 2.2407960725000002 4.3356632065 ZT8-11 5.0677005775 4.478888340999999 5.656512814000001 ZT12-15 5.18634763575 4.2519760785 6.120719193 ZT16-19 4.301174413249999 3.570739488 5.031609338499999 ZT20-23 7.48202868175 6.3036837939999995 8.6603735695