Not really, that's correlative inference with no justification...since school shootings are not happening in a bubble all done by some same hive mind. They're done by individuals, and the reasons vary but typically land on a brain malfunction.
Thus the asking of the question, is there a cause? And if so, what is it?
Seems unlikely that with 200 instances, that it would just be random chance.
Theres a cause, and it has nothing to do with what "type" of school they go to ~ thats really dopey because as far as anyone can tell, Schools themselves dont cause mental disabilities or sell guns to Minors.
So, how do you explain the discrepancy claimed in the op?
It doesn't require explanation because it's a bad inference.
1st of all, The Sandy Hook shooter wasn't an Elementary School student. He shot up a school that he wasn't even attending. Chew on that for 5 minutes until it hits you.
Bad inferences get you to really, super dumb places.
For instance, why are there Church and Mosque shootings in places of God-worship - and we haven't heard of one at a Satanic Temple? What are they doing right?!?!?!?
See how stupid that is?
You cannot make a statistical inference in a sample set as small as 200, especially as it pertains to schools because newsflash: only 10% of students in grades k-12 are in private school, and an even smaller percentage of that in catholic schools.
Of those students in catholic schools, 100% of them have had a place of their religious worship (we call them a Church) shot up somewhere in this Country.
^this is how we make bad inferences, when we're dummies.