condition mean min max ZT0-3 3.1793530000000003 3.1793530000000003 3.1793530000000003 ZT4-7 3.8832210000000003 3.8832210000000003 3.8832210000000003 ZT8-11 2.255307 2.255307 2.255307 ZT12-15 4.26304 4.26304 4.26304 ZT16-19 6.272191666666666 6.272191666666666 6.272191666666666 ZT20-23 7.084148 7.084148 7.084148