In my tiny corner of the photography world (automotive editorial), staff guys earn between $30-$45K. Beyond that, in the freelance/contract world, it's almost impossible to pin down an exact figure. On one end of the spectrum, there are people that work for nothing or next to nothing. They might only make a couple hundred dollars per year! They usually have full-time jobs in other professions, and shoot for fun. Some are itching to join a staff, but haven't had the opportunity to do so.
On the other end of the editorial spectrum, there are guys who would never join a staff because they make way more money on a contracted basis. Many got started working on a staff, but quit upon realizing the greater earning potential doing contracted work. Annual earning range between $50K-$100K. Most fall right in the middle. That said, most full-time freelance photographers that specialize in editorial work also dabble in some product and advertising photography as well.
The guys that clear $100K usually have a fair amount of public relations photography gigs, and do some editorial work on the side. By PR work, I referencing photographers that shoot images for OE manufacturers (GM, Ford, Chrysler, Honda, Toyota, BMW, etc) that will be distributed to media outlets.
The top dogs in the business are commercial photographers that don't even bother with editorial work. These are they guys shooting brochures, ad campaigns, and billboards. In the U.S., you can count these guys on one or two hands
Everyone aspires to be as good as them someday. They can charge hundreds of thousands of dollars per shoot, but they also have full-time staff members, hoards of assistants, and 18-wheelers full of equipment that rack up the expenses. Even so, they earn hundreds of thousands of dollars per year.
The unofficial hierarchy of earnings/prestige is:
1) Commercial photography
2) PR photography
3) Editorial photography
Of course, that's just my opinion