condition mean min max ZT0-3 4.25 4.25 4.25 ZT4-7 6.9 6.9 6.9 ZT8-11 5.7 5.7 5.7 ZT12-15 3.65 3.65 3.65 ZT16-19 5.949999999999999 5.949999999999999 5.949999999999999 ZT20-23 5.3 5.3 5.3