condition mean min max ZT0-3 16.992437 16.992437 16.992437 ZT4-7 15.611488000000001 15.611488000000001 15.611488000000001 ZT8-11 14.961074 14.961074 14.961074 ZT12-15 14.185915999999999 14.185915999999999 14.185915999999999 ZT16-19 13.9231005 13.9231005 13.9231005 ZT20-23 12.561566 12.561566 12.561566