condition mean min max ZT0-3 7.986423 7.986423 7.986423 ZT4-7 7.3903365 7.3903365 7.3903365 ZT8-11 7.164599 7.164599 7.164599 ZT12-15 7.51889 7.51889 7.51889 ZT16-19 7.1609425 7.1609425 7.1609425 ZT20-23 7.8568765 7.8568765 7.8568765