condition mean min max ZT0-3 3.334175 3.334175 3.334175 ZT4-7 2.26038 2.26038 2.26038 ZT8-11 1.9560499999999998 1.9560499999999998 1.9560499999999998 ZT12-15 2.490215 2.490215 2.490215 ZT16-19 3.324275 3.324275 3.324275 ZT20-23 2.84292 2.84292 2.84292