condition mean min max ZT0-3 12.144683333333333 11.0509 13.6948 ZT4-7 7.489185 7.489185 7.489185 ZT8-11 6.911235 6.911235 6.911235 ZT12-15 7.5054 6.183065 8.827735 ZT16-19 6.92844 6.92844 6.92844 ZT20-23 12.6914 12.6914 12.6914