Why are mass shootings becoming more common (since the 80s)?

[green for victory]

1. Before the introduction of Prozac in Dec. 1987, less than one percent of the population

Before the introduction of Prozac in Dec. 1987, less than one percent of the population in the U.S. was diagnosed with bipolar disorder – also known as manic depression. Now, with the widespread prescribing of antidepressants, the percent of the population in the United States that is diagnosed with bipolar disorder (swing from depression to mania or vice versa) has risen to 4.4%3 . This is almost one out of every 23 people in the U.S.

the one thing common in all of these shootings

http://ssristories.com/index.php

Why isn't this discussed in the mainstream media?