condition mean min max ZT0-3 7.033233333333333 3.918495 12.165 ZT4-7 6.589964999999999 6.589964999999999 6.589964999999999 ZT8-11 5.1607 5.1607 5.1607 ZT12-15 6.497375 6.116645 6.878105 ZT16-19 5.8932850000000006 5.8932850000000006 5.8932850000000006 ZT20-23 6.243115 6.243115 6.243115