(Undated) -- A new survey from Zillow shows Portland has among the fastest-rising rents in the nation. The survey places Portland at Number five, with the average rent increase at seven-point-two percent from January 2014 to January of this year. The median amount renters are paying is more than 15-hundred dollars a month. In the top spot is San Francisco, with an increase of nearly 15 percent and a median rent of more than three-thousand dollars.