cancerrt is rate of all cancer, white male for age 40.  Center for Disease Control data, Age specific rate (40) per 100,000 population.  Midrange is the middle of the range, which was 

>44.3-46.1
>41.3-44.3
>39.7-41.3
>36.2-39.7
29.5-36.2

These actual ranges don't appear

Note: from Perry Castenada map library -- look there for some other interesting maps (from CDC)

Digitized by James Monchak 2001.