In November, the rate of vacant Manhattan apartments rose to 2.87%—the highest in nine years, according to Bloomberg. Landlords’ inability to fill so many apartments might be due to the dizzying upward march of rent in the New York City borough, which has climbed for the past four years. In the year ending in November, median monthly rent jumped almost 4%, far outpacing inflation.

Manhattan landlords also have to compete with luxury buildings in Brooklyn and northwest Queens, where the median monthly rent is $2,935 and $2,735, respectively—far below Manhattan’s median $3,361 monthly rent.

Manhattan landlords are also sweetening leases more often this year, according to Bloomberg, offering to pay broker’s fees or a month’s rent in 14% of deals, compared with 4% last year.

“Complaining about high rents in Manhattan is nothing new, but now it’s becoming more visceral to tenants,” Jonathan Miller, president of appraiser Miller Samuel, told Bloomberg. Rent prices may fall as a result.

A study earlier this year conducted by StreetEasy found that New Yorkers spend the majority of their incomes on rent, with Manhattan residents spending around 48.8% of their incomes on a place to call home. Generally, a rent-to-income ratio of about 30% is considered affordable.