Financial recompense for blogging

I am interested in the amount of responses to the survey which emphasised the financial side of blogging. This might be indirect, ie one of the reasons that they blog is to market a product or part of their business. It might also be more direct - money raised by hosting advertising for example or career opportunities such as writing columns for newspapers or being contacted by publishers as a direct result of their blogging.
I begin to see that I should have asked for more detail about such financial recompensation for blogging in my survey. Although it now gives me the perfect opportunity to put together another grant application looking into this. How many bloggers are blogging because they think they can make money out of it? How many of these people will actually make money?