condition mean min max ZT0-3 3.75 3.75 3.75 ZT4-7 6.3 6.3 6.3 ZT8-11 7.2 7.2 7.2 ZT12-15 4.050000000000001 4.050000000000001 4.050000000000001 ZT16-19 6.85 6.85 6.85 ZT20-23 5.65 5.65 5.65