condition mean min max ZT0-3 8.446746 8.446746 8.446746 ZT4-7 7.9647515 7.9647515 7.9647515 ZT8-11 7.424570500000001 7.424570500000001 7.424570500000001 ZT12-15 7.787316500000001 7.787316500000001 7.787316500000001 ZT16-19 8.866874 8.866874 8.866874 ZT20-23 7.6490015 7.6490015 7.6490015