condition mean min max ZT0-3 11.8 11.8 11.8 ZT4-7 5.2 5.2 5.2 ZT8-11 5.75 5.75 5.75 ZT12-15 6.9 6.9 6.9 ZT16-19 3.75 3.75 3.75 ZT20-23 15.0 15.0 15.0