condition mean min max ZT0-3 21.0 21.0 21.0 ZT4-7 6.3 6.3 6.3 ZT8-11 16.35 16.35 16.35 ZT12-15 13.200000000000001 13.200000000000001 13.200000000000001 ZT16-19 6.85 6.85 6.85 ZT20-23 3.3 3.3 3.3