condition mean min max ZT0-3 3.7 3.7 3.7 ZT4-7 4.4 4.4 4.4 ZT8-11 20.950000000000003 20.950000000000003 20.950000000000003 ZT12-15 51.45 51.45 51.45 ZT16-19 14.75 14.75 14.75 ZT20-23 4.05 4.05 4.05