condition mean min max ZT0-3 18.3 18.3 18.3 ZT4-7 21.7 21.7 21.7 ZT8-11 8.25 8.25 8.25 ZT12-15 7.8500000000000005 7.8500000000000005 7.8500000000000005 ZT16-19 12.299999999999999 12.299999999999999 12.299999999999999 ZT20-23 39.8 39.8 39.8