More Semi-Auto gun, More Massacres - Coincidence?

Here is a chart of Mass Shootings in the US.  It is very striking to see.  As we get more Guns and specifically Semi-Automatic (Machine Guns really) weapons of war in the hands of average Joe Citizen, we have had a like increase in terrible tragedies.  The latest has been the shooting up of the Elementary School in Connecticut which left 20 little kids dead and 6 brave adults dead as well.

Houston, I feel we have a problem.

The more assault weapons on the street, the more mass shootings - Coincidence? I think Yes and I feel this chart bears out my thinking.