Maybe it's because the TV networks are deliberately not telling you about them.
According to a January 5, 2000 special report by Geoffrey Dickens, Senior Media Analyst of the Media Research Center, "In 1997, criminologist Gary Kleck estimated that over 2.5 million people a year defend themselves from an assailant or burglar by exercising their constitutional right to bear arms. Yet how many times did television networks report such acts? In the past two years, out of 653 gun policy stories, exactly 12 times. By making a blockbuster story out of several school shootings—while leaving out the millions of times citizens use guns to stop crime each year—they presented a very misleading picture to the average viewer that firearm use brings more harm than good, and thus should be limited or even banned."
The study further went on to document that instead of reporting on firearms in anything approaching an objective manner, "In 653 gun policy stories, those advocating more gun control outnumbered stories opposing gun control by 357 to 36, or a ratio of almost 10 to 1, while 260 were categorized as neutral. Anti-gun soundbites were twice as frequent as pro-gun ones—412 to 209—while 471 soundbites were neutral. Gun control advocates appeared on the morning shows as guests on 82 occasions, compared to just 37 for gun-rights activists and 58 neutral spokesmen."
Read "Outgunned: How the Network News Media Are Spinning the Gun Control Debate, a January 5, 2000 Special Report by the Media Research Center.