condition mean min max ZT0-3 6.5 6.5 6.5 ZT4-7 7.5 7.5 7.5 ZT8-11 6.2 6.2 6.2 ZT12-15 8.0 8.0 8.0 ZT16-19 6.05 6.05 6.05 ZT20-23 14.0 14.0 14.0