A Thursday report from Zillow revealed that renters in the United States are now spending an average of 30 percent of their income on housing, which is the highest share on record. Between 1995 and 2000, renters spent an average of 24 percent of their incomes. Among major cities, Los Angeles and San Francisco were the worst offenders, with averages of 49 percent and 47 percent, respectively. Yet mortgages are becoming more affordable, accounting for only 15 percent of salaries, according to Zillow’s figures. Analysts say the problem stems from demand outstripping supply and flat incomes.