condition mean min max ZT0-3 1.933772 1.933772 1.933772 ZT4-7 3.4499090000000003 3.4499090000000003 3.4499090000000003 ZT8-11 2.6035760000000003 2.6035760000000003 2.6035760000000003 ZT12-15 3.112632 3.112632 3.112632 ZT16-19 3.288265 3.288265 3.288265 ZT20-23 3.2023810000000004 3.2023810000000004 3.2023810000000004