condition mean min max ZT0-3 14.981595 6.021435 21.703 ZT4-7 6.005915 6.005915 6.005915 ZT8-11 4.356975 4.356975 4.356975 ZT12-15 6.508085 4.58193 8.43424 ZT16-19 9.81827 9.81827 9.81827 ZT20-23 16.80055 16.80055 16.80055