Link:
http://www.cmpa.com/Mediamon/mm0392.htmIt includes several graphs comparing positive and negative media coverage and type of coverage. It includes both the Democratic and Republican primaries. It is very interesting.
Note: Once again, I am not sure of what type of source it is.
On edit, here's one interesting tidbit: "George Bush and Bill Clinton both won despite receiving worse press than their rivals. Bush's coverage has been 76 percent negative, Clinton's 63 percent negative."
And, hey, I passed 1000 without even noticing!!!