A study by RentCafé has named Philadelphia among the top 10 rent-burdened cities in America, beating out cities like New York, San Francisco and Washington, DC.

While all three of those cities have higher median rents than Philly, the average annual income is proportionally higher as well. As a result, Philadelphians use an average of 40% of their income on rent, as opposed to 27% in San Francisco, 31% in Manhattan, 38% in Brooklyn and 33% in DC.

While much has been made of the wave of multifamily development in Philadelphia recently, the fact that virtually all the new construction has been Class-A means that the supply of more reasonably priced apartments has remained stagnant.

It goes beyond the affordable housing crisis to affect Millennials who pay higher rent to live in areas closer to their jobs, or with more to do. It's instructive for developers, who need to make sure that there are enough possible tenants making the money required to afford these new apartments. [RentCafé]