condition mean min max ZT0-3 2.7 2.7 2.7 ZT4-7 11.3 11.3 11.3 ZT8-11 20.9 20.9 20.9 ZT12-15 19.35 19.35 19.35 ZT16-19 12.0 12.0 12.0 ZT20-23 16.0 16.0 16.0