condition mean min max ZT0-3 3.4 3.4 3.4 ZT4-7 2.5 2.5 2.5 ZT8-11 4.6 4.6 4.6 ZT12-15 18.1 18.1 18.1 ZT16-19 3.0 3.0 3.0 ZT20-23 16.3 16.3 16.3