Why did the US economy slump in the 1970s and 1980s?

"The second "decline" of the U. S. economy took place in the 1970s and 80s. America’s international economic position fell markedly by the end of the 1960s and beginning of the 1970s. In 1970, the export trade of the six countries of the European Community accounted for 27.6% of the world total, more than doubling that of the United States (13.7%). The figure for Japan was 6.2%. In 1971, the United States suffered from a trade deficit, though the amount was small ($2.2 billion). Shortly, it rose to $6.8 billion in 1972, and since then, it occurred almost every year, which was totally different from what was before the 1970s. The case for Japan was just the opposite. Not only Japan experienced fast increase of its export trade but it also earned a surplus of $300 million in 1965 for the first time since the end of World War II. Its surplus increased annually to reach $5.17 billion in 1972, almost as much as the deficit ($6.8 billion) suffered by the United States in the same year. As regards the world gold reserve, the United States accounted for 29.9% of the total in 1970, which was much less than the European Community (36.9%). The position of the US dollar, though remaining the world’s principal reserve currency and settlement currency, had been clearly weakened, and that of the Deutsche mark and Japanese yen markedly risen. The "dollar shortage" in the initial years after World War II gradually became "dollar oversupply". This eventually led to the dollar crisis in the early 1970s. In 1971, the United States suspended the exchange of US dollars for gold, and various countries began to implement the floating exchange rate system. The Bretton Woods system centered on gold thus collapsed. This was an important symbol for America’s "decline"."