condition mean min max ZT0-3 7.406497 7.406497 7.406497 ZT4-7 6.7231135 6.7231135 6.7231135 ZT8-11 7.0775115 7.0775115 7.0775115 ZT12-15 7.4635145000000005 7.4635145000000005 7.4635145000000005 ZT16-19 6.7271825 6.7271825 6.7271825 ZT20-23 7.267877 7.267877 7.267877