Interesting Data on Masks
H/T Instapundit
Update:
After posting the link to this article, it has now been taken down. But the internet, as they say, is forever. I have two copies of this article if you're still interested in reading it.
I snagged a copy from the Wayback Machine. That copy is here.
I also generated a separate PDF with the original images (which were degraded in the Wayback Machine archive) and that copy is here.
Update 2:
Now the original link appears to be back. Go figure.