condition mean min max ZT0-3 14.519938333333334 12.89635 15.67565 ZT4-7 15.543099999999999 15.543099999999999 15.543099999999999 ZT8-11 16.43895 16.43895 16.43895 ZT12-15 20.986925 18.6169 23.356949999999998 ZT16-19 23.1958 23.1958 23.1958 ZT20-23 17.24825 17.24825 17.24825