condition mean min max ZT0-3 7.7 7.7 7.7 ZT4-7 2.2 2.2 2.2 ZT8-11 19.15 19.15 19.15 ZT12-15 10.95 10.95 10.95 ZT16-19 8.1 8.1 8.1 ZT20-23 15.75 15.75 15.75