condition mean min max ZT0-3 12.7 12.7 12.7 ZT4-7 0.9 0.9 0.9 ZT8-11 3.2 3.2 3.2 ZT12-15 2.25 2.25 2.25 ZT16-19 6.1 6.1 6.1 ZT20-23 19.7 19.7 19.7