condition mean min max ZT0-3 11.3 11.3 11.3 ZT4-7 1.2 1.2 1.2 ZT8-11 1.75 1.75 1.75 ZT12-15 2.1 2.1 2.1 ZT16-19 6.4 6.4 6.4 ZT20-23 22.75 22.75 22.75