Here is what I know.
The actual sale of singles in tracked by Billboard in their top 75 soundscan chart. That and the top 75 airplay chart or the basis for the Hot 100 chart. You will have to pick up a copy of Billboard Magazine to take a look at them or maybe they will give you access to it on the website after you pay to become a member.
Its difficult to tell sales data from just looking at the Hot 100 chart. There are songs every week that make it into the top 10 without being released as a single. Airplay is really what determines the Hot 100 chart today with Single Sales having a minor effect. A decade or so ago, it used to be 50% airplay and 50% sales which determined the chart. I do not know what the breakdown is today, but it is heavily in favor of airplay. I also don't have an exact mathemitical way to figure it out. But, I think realizing that you can make the top 10 without actually releasing a single, that tells you that sales of singles today really play a minor role.