. Increased use of pharmaceuticals?
2. Increased exposure to violence on TV?
3. Increased exposure to violence in video games?
4. Unknown/unrecognized societal factors and pressures?
All the above and that does not mean government should "fix" or pass laws however right now those in charge prefer to blame an inanimate objects "firearms" for all the problems in our society and in my opinion we have larger issues including the above 1-4.