condition mean min max ZT0-3 8.782575 8.782575 8.782575 ZT4-7 8.072486000000001 8.072486000000001 8.072486000000001 ZT8-11 8.586478 8.586478 8.586478 ZT12-15 9.378560499999999 9.378560499999999 9.378560499999999 ZT16-19 8.6961425 8.6961425 8.6961425 ZT20-23 8.28853 8.28853 8.28853