condition mean min max ZT0-3 8.45 8.45 8.45 ZT4-7 5.9 5.9 5.9 ZT8-11 4.75 4.75 4.75 ZT12-15 9.35 9.35 9.35 ZT16-19 18.0 18.0 18.0 ZT20-23 19.4 19.4 19.4