condition mean min max ZT0-3 15.871963333333333 7.76724 22.1467 ZT4-7 5.985855 5.985855 5.985855 ZT8-11 6.453984999999999 6.453984999999999 6.453984999999999 ZT12-15 7.10875 5.6700099999999996 8.54749 ZT16-19 9.838519999999999 9.838519999999999 9.838519999999999 ZT20-23 18.6017 18.6017 18.6017