condition mean min max ZT0-3 2.072465 1.62794 2.51699 ZT4-7 1.636765 1.636765 1.636765 ZT8-11 2.0555149999999998 2.0555149999999998 2.0555149999999998 ZT12-15 0 0 0 ZT16-19 2.13431 2.13431 2.13431 ZT20-23 2.027435 2.027435 2.027435