condition mean min max ZT0-3 8.82841 8.82841 8.82841 ZT4-7 7.456775 7.456775 7.456775 ZT8-11 7.82285 7.82285 7.82285 ZT12-15 8.21464 8.21464 8.21464 ZT16-19 8.896015 8.896015 8.896015 ZT20-23 8.353784999999998 8.353784999999998 8.353784999999998