How much is an average New Yorker with a degree, good job, and great apartment earn?

I notice that there are very expensive apartments in New York and while looking for an apartment for my friend last week I found out that apartments go from $2,000 a month for a studio to $3,000 for a one bedroom. Most of these rented by one person, I was wondering what kind of work do these ppl do in general and how much do they earn an hour. And is the rent half or just a third of their salary.