condition mean min max ZT0-3 7.2 7.2 7.2 ZT4-7 9.4 9.4 9.4 ZT8-11 7.1 7.1 7.1 ZT12-15 4.85 4.85 4.85 ZT16-19 4.300000000000001 4.300000000000001 4.300000000000001 ZT20-23 4.9 4.9 4.9