condition mean min max ZT0-3 3.887823333333333 3.263065 4.698079999999999 ZT4-7 3.7791550000000003 3.7791550000000003 3.7791550000000003 ZT8-11 4.137919999999999 4.137919999999999 4.137919999999999 ZT12-15 6.810499999999999 6.544665 7.076334999999999 ZT16-19 6.68015 6.68015 6.68015 ZT20-23 6.7638300000000005 6.7638300000000005 6.7638300000000005