condition mean min max ZT0-3 6.4 6.4 6.4 ZT4-7 2.5 2.5 2.5 ZT8-11 5.0 5.0 5.0 ZT12-15 20.0 20.0 20.0 ZT16-19 30.3 30.3 30.3 ZT20-23 16.05 16.05 16.05