condition mean min max ZT0-3 20.781225 18.665599999999998 22.89685 ZT4-7 17.32965 17.32965 17.32965 ZT8-11 12.18235 12.18235 12.18235 ZT12-15 0 0 0 ZT16-19 18.0842 18.0842 18.0842 ZT20-23 19.1231 19.1231 19.1231