condition mean min max ZT0-3 6.75 6.75 6.75 ZT4-7 2.9 2.9 2.9 ZT8-11 12.7 12.7 12.7 ZT12-15 4.2 4.2 4.2 ZT16-19 16.15 16.15 16.15 ZT20-23 28.6 28.6 28.6