" During his final year in office, at the height of the Cold War, the U.S. government posted a more than $1 billion surplus. In 2013, the federal deficit topped $680 billion, down from $1.1 trillion in 2012. As of this writing, the U.S. national debt has surpassed $18 trillion. For perspective, in 1960, the national debt was about 52 percent of the country’s gross domestic product. By 1970, that figure had fallen to 34 percent. On October 17, 2013, it passed the 100 percent mark. In other words, the national debt now exceeds the value of America’s entire economic output. "

― Ian Bremmer , Superpower: Three Choices for America's Role in the World