While the number of low-income renter households has continued to grow, the supply of available and affordable rental units has not, according to new research by the National Low Income Housing Coalition (NLIHC).

In 2012, the number of extremely low-income (ELI) renter households, those earning 30 percent or less of the area median income (AMI), rose to 10.3 million. On top of that growing figure was a shortage of 7.1 million affordable rental units available to those households. That means only 31 affordable rental units were available for every 100 ELI households.

In addition, for the 4 million deeply low-income (DLI) renter households, those earning 15 percent or less of the AMI, there was a shortage of 3.4 million available and affordable rental units, meaning there were only 16 affordable and available rental units for every 100 DLI households in 2012.

The research shows that no state has sufficient affordable rental units available for ELI and DLI households, but some states are worse off than others.

In 2012, Nevada only had 15 available and affordable housing units per 100 ELI renter households, followed by Arizona and California, with 20 units. For the DLI renters, Wisconsin only had nine units of affordable and available housing per 100 households, followed by 10 units in Nevada and New Mexico.

The states with the most available and affordable housing units for ELI renter households were South Dakota with 54 units and North Dakota with 52 units. However, no state had more than 34 available and affordable housing units for the DLI renter households.

The renter households in 2012 also were severely cost burdened, with 75 percent of the ELI renters and 90 percent of the DLI renters spending more than half their incomes on rent and utilities.

Despite this need, most of the new rental units coming online are not affordable to these income groups, says the NLIHC. Between 2009 and 2012, 2.5 million rental units were added, and more than 1.5 million of them only were affordable to households earning 80 percent or more of the AMI.

The research shows that affordable housing developers need more capital and operating support to serve the ELI and DLI renter households.  The NLIHC continues to advocate for the National Housing Trust Fund, which was established in 2008 and has yet to be funded.

The trust fund would provide developers with dedicated sources of revenue to expand and preserve the nation’s supply of affordable rental housing for these low-income households.