condition mean min max ZT0-3 17.027475 17.027475 17.027475 ZT4-7 19.071272 19.071272 19.071272 ZT8-11 16.3415635 16.3415635 16.3415635 ZT12-15 16.103222000000002 16.103222000000002 16.103222000000002 ZT16-19 14.3279265 14.3279265 14.3279265 ZT20-23 14.835902 14.835902 14.835902