condition mean min max ZT0-3 2.648265 2.648265 2.648265 ZT4-7 1.9780449999999998 1.9780449999999998 1.9780449999999998 ZT8-11 1.5351650000000001 1.5351650000000001 1.5351650000000001 ZT12-15 1.722175 1.722175 1.722175 ZT16-19 2.576535 2.576535 2.576535 ZT20-23 1.5281449999999999 1.5281449999999999 1.5281449999999999