condition mean min max ZT0-3 15.195948 15.195948 15.195948 ZT4-7 13.344808 13.344808 13.344808 ZT8-11 13.0818245 13.0818245 13.0818245 ZT12-15 12.341591999999999 12.341591999999999 12.341591999999999 ZT16-19 11.824778 11.824778 11.824778 ZT20-23 12.8930965 12.8930965 12.8930965