Just be careful with taking any single site as gospel, particularly Marshall’s. He and Sanow built their models without any real scientific statical analysis used. It was pure interpretation of data and no scientific method applied. The other thing to be careful of when determining that all elusive “stopping power” is that there are several thoughts about the matter.
All I am saying is that this is a good resource for some data, but make sure you use multiple sources and analyze your data appropriately before applying it.
http://ageofdecadence.com