condition mean min max ZT0-3 6.15 6.15 6.15 ZT4-7 4.0 4.0 4.0 ZT8-11 6.800000000000001 6.800000000000001 6.800000000000001 ZT12-15 3.0 3.0 3.0 ZT16-19 2.3 2.3 2.3 ZT20-23 5.65 5.65 5.65