condition mean min max ZT0-3 5.867005 3.820715 7.17682 ZT4-7 5.040805 5.040805 5.040805 ZT8-11 5.70981 5.70981 5.70981 ZT12-15 6.116005 5.791095 6.440915 ZT16-19 7.07746 7.07746 7.07746 ZT20-23 8.122715 8.122715 8.122715