condition mean min max ZT0-3 3.0 3.0 3.0 ZT4-7 16.7 16.7 16.7 ZT8-11 2.1 2.1 2.1 ZT12-15 4.0 4.0 4.0 ZT16-19 9.0 9.0 9.0 ZT20-23 7.55 7.55 7.55