condition mean min max ZT0-3 9.847212 9.847212 9.847212 ZT4-7 7.6818165 7.6818165 7.6818165 ZT8-11 7.278255 7.278255 7.278255 ZT12-15 8.231965500000001 8.231965500000001 8.231965500000001 ZT16-19 7.7127735 7.7127735 7.7127735 ZT20-23 7.487553 7.487553 7.487553