The Bureau of Labor Statistics has the numbers:

This is also interesting from a political perspective, as these two fields, while being so similar (writing that tries to grab your attention) have much different norms:

Journalism: Comfort the afflicted and afflict the comfortable.

Public relations: Serve the client (who is likely to be comfortable).

An interesting subfield here is science writing, where so much of journalism actually takes the form of public relations, reporting hype about cancer cures, etc.

This is not to say that people who work in P.R. are bad guys — after all, it’s not part of my charter as a statistician to comfort the afflicted and afflict the comfortable, either — nor would it be my role to cast such judgments. I would just think that, to the extent that we’re getting less of our news from journalism and more from public relations (and from independent sources such as this blog — yes, we’re at The Washington Post, but we aren’t doing this for a living), this would have some political effects.

Along these lines, Mark Palko (another information provider who is employed neither in journalism nor in public relations) writes:

For a variety of reasons, including but not limited to downsizing, an increasingly insular culture, and a shift to a star system that serves to hollow out the middle of the profession, journalism became both less diligent about maintaining quality and hungrier for free content (an appetite greatly expanded by online forums). While things changes were happening, companies were also growing more experienced at measuring and manipulating public opinion.

The decline in journalism created an extraordinary opportunity for corporate PR departments. News stories that portrayed products and companies in a favorable light were both more persuasive than traditional advertising and considerably cheaper.

Palko continues:

My biggest concerns about the role of PR in modern journalism are not the question of accuracy or bias, though both of those are important. What really concerns me is the way these outside influences determine what does and does not get covered and the lack of awareness (or at least acknowledgement) on the part of the press.