condition mean min max ZT0-3 3.2 3.2 3.2 ZT4-7 8.0 8.0 8.0 ZT8-11 33.0 33.0 33.0 ZT12-15 20.9 20.9 20.9 ZT16-19 9.75 9.75 9.75 ZT20-23 24.8 24.8 24.8