The chart above shows the change in incomes and rents, broken down by income quintiles, for D.C. renter households between 2002 and 2013. It comes from a report published this morning by the D.C. Fiscal Policy Institute titled “Going, Going, Gone: DC’s Affordable Housing Crisis.”

The report is an update on a 2012 study by DCFPI, which found that more than half of low-cost rental units (defined as those renting for under $750, in inflation-adjusted dollars) had vanished since 2000. Today’s report has similar findings. After nudging the cost threshold up to $800 to keep up with inflation, the report’s author, Wes Rivers, finds that the number of apartments renting for less than $800 per month dropped from nearly 60,000 in 2002 to about 33,000 in 2013, in 2013 dollars.

The $800 figure, says Rivers, is based on two measures. It represents the cheapest fifth of the rental stock, and for a family of four at the poverty line, it represents about 42 percent of income going to rent—higher than the 30 percent threshold that’s typically used to determine affordability, but still less than most very low-income families are paying toward rent.

Still, it’s a somewhat arbitrary definition of affordability. And the notion that D.C. housing is rapidly growing more expensive is hardly novel.

Instead, the bigger surprise from the report is the gaping discrepancy between income and rent growth. The lowest-income 40 percent of renters saw no statistically significant income growth over the past decade, but saw large rent increases: 14 percent in the lowest quintile and 35 percent in the second-lowest quintile. But it’s actually not the poorest Washingtonians who saw their incomes fall farthest behind their rents. Instead, it’s the middle quintile of renters, whose incomes rose just 9 percent while their rents jumped 44 percent.

Even the wealthiest renters haven’t been spared. The top quintile saw 9 percent income growth but 32 percent rent growth.

Granted, poorer renters are still having a much harder time paying the bills. According to the report, 64 percent of households making under 30 percent of area median income pay more than half of their income in rent—a hardship known as a “severe rent burden”—up from 50 percent in 2002. That figure is 31 percent for households making between 30 and 50 percent of area median income. For households making above the area median, it’s zero.

“D.C.’s economy has definitely left some income-earners behind,” says Rivers. “We looked at the bottom 40 percent of renters, and it’s clear that their incomes have stagnated over the last 10 years.”

The report also finds that the private market no longer supplies many, if any, apartments renting for under $800 a month. According to DCFPI, the number of apartments that cost less than $800 is roughly equivalent to the number of federally and locally subsidized apartments, which “suggests that subsidized housing is now virtually the only source of inexpensive apartments,” the report states.

Rising rents on their own aren’t necessarily alarming, since they can simply reflect higher incomes. But when rents outpace incomes so significantly, it suggests that demand for D.C. housing is outstripping supply at nearly every income level.

“There’s definitely an issue of supply,” says Rivers. “Increasingly, we’re seeing that middle-income renters are starting to face that as well.”

Chart from DCFPI