Several paragraphs into an informative Wall Street Journal story on why the housing market isn’t boosting the U.S. economy, there was an incredible factoid.

The percentage of homeowners who are underwater — that is, owing more on a mortgage than the home is worth — is 8.7%, down from 21% at the end of 2011, according to CoreLogic. However, the percentage of homeowners who believe they are underwater is 27%, according to separate data from Fannie Mae.