condition mean min max ZT0-3 11.7 11.7 11.7 ZT4-7 14.9 14.9 14.9 ZT8-11 10.75 10.75 10.75 ZT12-15 21.85 21.85 21.85 ZT16-19 5.75 5.75 5.75 ZT20-23 8.6 8.6 8.6