New York City's already an expensive place to live — and it's only getting more expensive, especially if you are renting in Manhattan.

The median rent jumped more than 9 percent in the first three months of this year compared to the same time last year, according to real estate brokerage firm Prudential Douglas Elliman and real estate appraisal and consulting firm Miller Samuel.

The median Manhattan rent is now $3,064, up from just over $2,808 for the same period a year ago, according to the report. That includes any concession, like a month of free rent, that a landlord might offer. The median for a one-bedroom for the first quarter of 2012 was $3,195, up from $2,970 during the same time frame in 2011.

Typically, rising rents are a sign of a strong economy, but Jonathan Miller, CEO of Miller Samuel, said this jump is due the availability of mortgages rather than improving economic conditions.

“It has nearly everything to do with access to credit,” he said. When people can't get a mortgage to buy a house in the neighborhood where they want to live, they’re forced to rent. More renters drives up prices.  

Average rents in the city have reached an all time high, according to a separate report, released Thursday from real estate broker Citi Habitats. Their findings, which rely on a different set of data and track averages instead of medians, show that the average Manhattan apartment rented for $3,418 during March 2012 — the highest amount since 2002, when Citi Habitats first began tracking this data.  The previous record — set in May of 2007 — was $3,394.