condition mean min max ZT0-3 1.7807248333333332 1.1773795 2.1148249999999997 ZT4-7 2.200415 2.200415 2.200415 ZT8-11 2.368835 2.368835 2.368835 ZT12-15 3.0915250000000003 2.56341 3.6196400000000004 ZT16-19 2.2705200000000003 2.2705200000000003 2.2705200000000003 ZT20-23 3.23138 3.23138 3.23138