Federal Debt Held by Foreign & International Investors as Percent of Gross Domestic Product (HBFIGDQ188S) (https://fred.stlouisfed.org/series/HBFIGDQ188S) was first constructed by the Federal Reserve Bank of St. Louis in October 2012. It is calculated using Federal Debt Held by Foreign & International Investors (FDHBFIN) (https://fred.stlouisfed.org/series/FDHBFIN) and Gross Domestic Product, 1 Decimal (GDP) (https://fred.stlouisfed.org/series/GDP): (FDHBFIN/GDP)*100