The National League of Cities reports the Joint Center for Housing Studies at Harvard University says the availability of affordable housing for lower income families continues to fall as the demand increases.  The affordable rental housing stock is declining due to abandonment of older buildings and conversion of property to other uses.  Meanwhile, the low-cost units that are available tend to be higher-risk housing that may jeopardize the health and safety of residents.  Affordable housing is defined as the cost of rent and utilities equaling less than 30 percent of household income.  Approximately 25 percent of the renter population of 10.1 million in 2009 spent over 50 percent of their household income for housing.  The number of people classified as needing affordable housing increased 1.7 million from 2003 to 2009.