condition mean min max ZT0-3 2.4 2.4 2.4 ZT4-7 1.0 1.0 1.0 ZT8-11 1.2 1.2 1.2 ZT12-15 11.4 11.4 11.4 ZT16-19 4.3 4.3 4.3 ZT20-23 3.25 3.25 3.25