[Gregrrr]

For one, they're all in Canada, or they're way out in Alaska, Montana, or Colorado. The Pioneers killed all of the grizzlies in our (broad) area because of their aggressive behavior. The experts say they haven't seen one in Washington's cascades for decades, even with the motion detector cameras they have out there.
Two, this is all of the deaths in all of North America. All of the odds are against anything ever happening.
Three, look at the cougar page on wikipedia, you'll see most of them are over 70, or were little kids plucked right from their front yards. Not a huge threat to a few 6 foot tall people on the trail.
Four, I'm not saying I don't pucker up when I see a huge paw print in the mud...