condition mean min max ZT0-3 8.966579201 7.539537345 10.393621057 ZT4-7 7.413739964666666 5.963459870333334 8.864020059 ZT8-11 7.058608156 7.054149620666667 7.063066691333334 ZT12-15 7.6072738595 5.768767231 9.445780488 ZT16-19 8.4533219815 7.50844542 9.398198543000001 ZT20-23 7.2744505685 6.373413759333333 8.175487377666666