though current account surpluses returned and grew quickly. From ¥221 per US$ in 1981, the average value of the yen actually dropped to ¥239 per US$ in 1985. The rise in the current account surplus generated stronger demand for yen in foreign-exchange markets, but this trade-related demand for yen was offset by other factors. A wide differential in interest rates, with United States interest rates much higher than those in Japan, and the continuing moves to deregulate the international flow of capital, led to a large net outflow of capital from Japan. This capital flow increased the supply of yen in foreign-exchange markets, as Japanese investors changed their yen for other currencies (mainly dollars) to invest overseas. This kept the yen weak relative to the dollar and fostered the rapid rise in the Japanese trade surplus that took place in the 1980s. Effect of the Plaza Accord In 1985, a dramatic change began. Finance officials from major nations signed an agreement (the Plaza Accord) affirming that the dollar was overvalued (and, therefore, the yen undervalued). This agreement, and shifting supply and demand pressures in the markets, led to a rapid rise in the value of the yen. From its average of ¥239 per US$ in 1985, the yen rose to a peak of ¥128 in 1988, virtually doubling its value relative to the dollar. After declining somewhat in 1989 and 1990, it reached a new high of ¥123 to US$ in December 1992. In April 1995, the yen hit a peak of under 80 yen/US$, temporarily making Japan's economy nearly the size of that of the US. Post-bubble years The yen declined during the Japanese asset price bubble and continued to do so afterwards, reaching a low of ¥134 to US$ in February 2002. The Bank of Japan's policy of zero interest rates has discouraged yen investments, with the carry trade of investors borrowing yen and investing in better-paying currencies (thus further pushing down the yen) estimated to be as large as $1 trillion. In February 2007, The Economist estimated that the yen was 15% undervalued against the dollar, and as much as 40% undervalued against the euro. After the global economic crisis of 2008 However, this trend of depreciation reversed after the global economic crisis of 2008. Other major currencies, except the Swiss franc, have been declining relative to the yen. On April 4, 2013, the Bank of Japan