Throughout the early 2000s, federal debt held by the public—the amount of outstanding U.S. Treasury securities (Treasuries) held by the Federal Reserve System and private investors—was stable at around 35 percent of gross domestic product (GDP). Since the financial crisis of 2007-08, however, the federal debt has grown significantly. As of 2017:Q4, debt held by the public was 75 percent of GDP.
[...] one way to interpret the evidence is that the demand for Treasury debt grew more rapidly than its supply (as evidenced by very low bond yields, for example). What was the source of this elevated demand for Treasury debt?
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