condition mean min max ZT0-3 9.970968333333333 1.9314050000000003 16.70985 ZT4-7 2.93977 2.93977 2.93977 ZT8-11 3.3899150000000002 3.3899150000000002 3.3899150000000002 ZT12-15 6.67132 3.86464 9.478 ZT16-19 10.87984 10.87984 10.87984 ZT20-23 15.8875 15.8875 15.8875