condition mean min max ZT0-3 10.75 10.75 10.75 ZT4-7 3.9 3.9 3.9 ZT8-11 5.75 5.75 5.75 ZT12-15 7.4 7.4 7.4 ZT16-19 16.2 16.2 16.2 ZT20-23 9.95 9.95 9.95