condition mean min max ZT0-3 6.257835 6.257835 6.257835 ZT4-7 3.974955 3.974955 3.974955 ZT8-11 6.9262250000000005 6.9262250000000005 6.9262250000000005 ZT12-15 5.78786 5.78786 5.78786 ZT16-19 9.68812 9.68812 9.68812 ZT20-23 8.567515 8.567515 8.567515