condition mean min max ZT0-3 3.1821883333333334 2.79981 3.4164250000000003 ZT4-7 1.94153 1.94153 1.94153 ZT8-11 2.222835 2.222835 2.222835 ZT12-15 3.2087950000000003 2.7941000000000003 3.6234900000000003 ZT16-19 2.750375 2.750375 2.750375 ZT20-23 3.5316549999999998 3.5316549999999998 3.5316549999999998