A new report found that Virginia is short at least 200,000 affordable rental units as many residents struggle to afford the cost of housing. The findings, presented by the state’s Joint Legislative and Audit Review Commission, were part of a larger review of affordability and potential impacts on supply and demand, including the effectiveness of existing state housing programs. Analysts for the state watchdog agency found that nearly 30 percent of Virginia households are “cost-burdened,” a measure that refers to people who spend more than 30 percent of their income on housing.