condition mean min max ZT0-3 7.319215 4.300075 9.40192 ZT4-7 4.79497 4.79497 4.79497 ZT8-11 3.6367599999999998 3.6367599999999998 3.6367599999999998 ZT12-15 5.2996525000000005 4.652185 5.94712 ZT16-19 8.084735 8.084735 8.084735 ZT20-23 9.069355 9.069355 9.069355