condition mean min max ZT0-3 8.30124 8.30124 8.30124 ZT4-7 8.296694 8.296694 8.296694 ZT8-11 7.5066725000000005 7.5066725000000005 7.5066725000000005 ZT12-15 7.2944765 7.2944765 7.2944765 ZT16-19 7.7746390000000005 7.7746390000000005 7.7746390000000005 ZT20-23 7.798439 7.798439 7.798439