I'm sorry but even if you could prove that a lot of media outlets didn't cover the Fast & Furious scandal it wouldn't mean anything.
Because what's more likely:
That big media conglomerates decided a complex issue of importance to a limited segment of the population might not garner bigger ratings than in-depth analysis of Justin Beiber and the Royal Wedding...
...
or...
...that they decided to bury the story lest it look bad for their main man Obama who they have strangely decided to air bad stories about in the past anyways?