condition mean min max ZT0-3 13.2 13.2 13.2 ZT4-7 6.8 6.8 6.8 ZT8-11 5.15 5.15 5.15 ZT12-15 2.4 2.4 2.4 ZT16-19 4.1 4.1 4.1 ZT20-23 2.95 2.95 2.95