condition mean min max ZT0-3 15.341971 15.341971 15.341971 ZT4-7 13.9717215 13.9717215 13.9717215 ZT8-11 18.897152 18.897152 18.897152 ZT12-15 25.037824999999998 25.037824999999998 25.037824999999998 ZT16-19 19.691045000000003 19.691045000000003 19.691045000000003 ZT20-23 21.530993 21.530993 21.530993