My mind is swirling from looking at so many numbers as we finish this issue of Affordable Housing Finance, which features the annual AHF 50, our exclusive rankings of the top owners and developers in the nation.

In terms of developers' starts, there was a 17 percent drop between the rebound year of 2010 and 2011. The 53 companies in this year's developers list started 232 new construction projects with 19,053 affordable housing units last year.

These levels are still healthy compared with the lows of 2009, when the Top 50 developers only started 182 projects with 16,711 units.

However, it's the numbers in two recent reports that have me concerned and show how dire the affordable housing situation is for some of America's low-income households.

Nearly 1 in 4 working households spends more than half of its income on housing. The share of working households with a severe housing cost burden increased significantly between 2008 and 2010, rising from 21.8 percent to 23.6 percent, according to the Center for Housing Policy's “Housing Landscape 2012” report.

The increase in the rate of severe housing cost burden among working households occurred primarily for those earning less than 80 percent of the area median income (AMI), with the severe housing cost burden increasing the most for those earning less than 50 percent of the AMI.

The percentage of working households earning between 31 percent and 50 percent of the AMI with a severe cost burden increased from 35.8 percent to 40.6 percent. For those earning 30 percent or less of the AMI, it went from 78.3 percent to 80.9 percent.

The National Low Income Housing Coalition (NLIHC) provides another way of looking at the affordable housing need. It found through an analysis of the 2010 American Community Survey Public Use Microdata Sample that the gap between the number of renter households with very low incomes and extremely low incomes and the number of rental housing units that are affordable and available to these households is widening.

For every 100 extremely low-income renter households, those earning less than 30 percent of the metropolitan area median family income, the NLIHC found that there are only 30 affordable and available units. For every 100 very low-income renter households, those earning between 31 percent and 50 percent of the median family income, there are only 58 affordable and available units.

With the shortage of affordable housing units and the severe housing cost burdens, the consequences for some of the nation's most low-income households could be dire.

NLIHC President Sheila Crowley sums it up well, saying there are millions of families whose incomes are so low and whose housing costs are so high that all it would take is a few days out of work with a sick child or one high heating bill to push them into homelessness.