These kinds of questions are exactly the type of justifications given for national gun registrations. Without a database of gun owners, it's difficult to run stats to identify trends and compare datasets.
Looking at NICS checks, ATF forms filed, registrations in states that require it, and other data doesn't capture all of the sales, transfers and losses of firearms.
Too bad no one has come up with a way of anonymously reporting aggregate figures for comparisons. I can see a use for that, if for no other reason, to support market research.