condition mean min max ZT0-3 20.61075 18.8089 22.412599999999998 ZT4-7 11.1463 11.1463 11.1463 ZT8-11 7.45538 7.45538 7.45538 ZT12-15 0 0 0 ZT16-19 14.5596 14.5596 14.5596 ZT20-23 20.667 20.667 20.667