condition mean min max ZT0-3 18.4 18.4 18.4 ZT4-7 12.1 12.1 12.1 ZT8-11 12.700000000000001 12.700000000000001 12.700000000000001 ZT12-15 17.95 17.95 17.95 ZT16-19 7.5 7.5 7.5 ZT20-23 16.25 16.25 16.25