condition mean min max ZT0-3 16.5787 13.56085 18.59045 ZT4-7 8.124035 8.124035 8.124035 ZT8-11 9.02914 9.02914 9.02914 ZT12-15 19.182575 18.5019 19.86325 ZT16-19 19.154049999999998 19.154049999999998 19.154049999999998 ZT20-23 22.087699999999998 22.087699999999998 22.087699999999998