condition mean min max ZT0-3 1.6991133333333333 0.48797 2.38801 ZT4-7 0.7258365 0.7258365 0.7258365 ZT8-11 1.1292499999999999 1.1292499999999999 1.1292499999999999 ZT12-15 2.61558 2.319815 2.911345 ZT16-19 3.11191 3.11191 3.11191 ZT20-23 3.59088 3.59088 3.59088