condition mean min max ZT0-3 18.112425 17.2085 19.016350000000003 ZT4-7 15.22345 15.22345 15.22345 ZT8-11 23.05165 23.05165 23.05165 ZT12-15 0 0 0 ZT16-19 21.769 21.769 21.769 ZT20-23 18.81375 18.81375 18.81375