condition mean min max ZT0-3 3.390945 2.31181 5.144335 ZT4-7 3.108515 3.108515 3.108515 ZT8-11 2.6575699999999998 2.6575699999999998 2.6575699999999998 ZT12-15 6.06882 5.05228 7.08536 ZT16-19 3.325705 3.325705 3.325705 ZT20-23 2.3686249999999998 2.3686249999999998 2.3686249999999998