condition mean min max ZT0-3 217.771599 217.771599 217.771599 ZT4-7 220.867482 220.867482 220.867482 ZT8-11 268.1851595 268.1851595 268.1851595 ZT12-15 246.26990999999998 246.26990999999998 246.26990999999998 ZT16-19 291.1766095 291.1766095 291.1766095 ZT20-23 241.308448 241.308448 241.308448