This Friday, Feb. 27, 2015, photo shows a sign advertising a house for rent in Los Angeles. More than one-in-four renters must devote at least half of their family income to housing and utilities, according to a new analysis of Census data by Enterprise Community Partners, a nonprofit that helps finance affordable housing. AP Photo/Richard Vogel Housing supply is incredibly tight.

Deutsche Bank economist Torsten Slok highlighted the chart below in his housing chartbook for May showing that rental vacancy rate has not been this low in at least 20 years.

This tight supply, coupled with high demand has pushed up rental prices.

A story by the Associated Press on Friday noted that one in four renters spend more than half of their income on housing and utility costs. That's more than the 30% threshold the government considers as a convenient share of monthly income.

Deutsche Bank notes that this has consequences for future inflation and construction activity.

This one paragraph from the AP story ties it together: "The crisis reflects one of the shortcomings of the recovery: Wages have failed to match rising rental prices. At the same time, construction has failed to keep pace with demand from renters. The recession pushed more millennials, former homeowners who faced foreclosure and low-wage workers into rental housing."