The Series Is Based On The Number Of 1-4 Family Mortgage Loans Outstanding And Includes Loans In Foreclosure. Source: Mortgage Bankers Association Of America, "National Delinquency Survey"
This NBER data series q09084 appears on the NBER website in Chapter 9 at http://www.nber.org/databases/macrohistory/contents/chapter09.html.
NBER Indicator: q09084
Release: NBER Macrohistory Database
National Bureau of Economic Research, Mortgage Delinquency Rates for United States [Q09084USQ507NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q09084USQ507NNBR/, October 9, 2015.