ニクソン・ショック
The US dollar (USD) has been considered a strong currency for much of its history. Despite the Nixon Shock of 1971, and the United States' growing fiscal and trade deficits, most of the world's monetary systems have been tied to the US dollar due to the Bretton Woods System and dollarization. Countries have thus been compelled to purchase dollars for their foreign exchange reserves, denominate their commodities in dollars for foreign trade, or even use dollars domestically, thus buoying the currency's value.