Cincinnati mortgages are among the most affordable in the U.S. despite a sharp rise in mortgage burdens nationwide, a recent report suggests. The Queen City ranked second only to Pittsburgh as having the lowest income-to-mortgage payment ratio among the nation’s hottest housing markets. Estimating a 5 percent interest rate, Cincinnatians spend just 13.2 percent of their income on mortgage payments. That’s according to a new report from Zillow Inc.