When are signals on the air from North America and how strong are they?

Data from QS1R 7 band receiver and VE3NEA Skimmer Server

Data from Feb 10-11, 2010

I am trying to decide what the most useful approach would be to analyzing CW Skimmer log data. Spot Collector makes it trivial to sort the data by continent and band. I could create a graph like the one above for each continent. The one issue I have with this is that it fails to give a reasonable picture of the large spread in signal to noise ratios for each of the bands. So I could make available graphs like the one below with a scatter plot for each band and continent. But I doubt that this is worth 40 or so graphs which would need to redone through the solar cycle.

What do you think? What would be useful. Does anyone have a better idea for treating these data with some statistical rigor? I would like to hear your comments by email.