condition mean min max ZT0-3 15.76605 15.36595 16.16615 ZT4-7 12.5815 12.5815 12.5815 ZT8-11 15.68635 15.68635 15.68635 ZT12-15 0 0 0 ZT16-19 19.148850000000003 19.148850000000003 19.148850000000003 ZT20-23 17.54825 17.54825 17.54825