condition mean min max ZT0-3 3.9 3.9 3.9 ZT4-7 2.7 2.7 2.7 ZT8-11 1.2 1.2 1.2 ZT12-15 16.7 16.7 16.7 ZT16-19 12.2 12.2 12.2 ZT20-23 6.2 6.2 6.2