condition mean min max ZT0-3 6.788888889 6.788888889 6.788888889 ZT4-7 7.523888889 7.523888889 7.523888889 ZT8-11 6.938888889 6.938888889 6.938888889 ZT12-15 5.462222222333334 5.462222222333334 5.462222222333334 ZT16-19 4.34 4.34 4.34 ZT20-23 4.855555555666667 4.855555555666667 4.855555555666667