With the exception of a blip in May 2010 and again in November, caused on both occasions by a rise in risk aversion among global investors as the sovereign debt crisis in Europe unfolded, the rupiah has followed an appreciating trend against the US dollar since March 2009. As of mid-January 2011 the currency was trading at around Rp9,025:US$1. Interest from international investors in carry trades (whereby speculators borrow in countries where interest rates are low, such as the US and Japan, in order to purchase assets in countries with higher rates, such as Indonesia) has been an important factor in the rupiah's appreciation. Healthy domestic economic growth in spite of the 2008-09 global recession has been another factor encouraging foreign investment in Indonesian assets. Large capital inflows are expected in 2011, when Indonesia's GDP growth rate will compare favourably with that in Western economies, but BI will intervene if necessary to prevent the currency from appreciating too sharply. After appreciating by an estimated 14.3% on an annual average basis in 2010, to Rp9,090:US$1, the rupiah is forecast to continue to strengthen in 2011 before weakening gradually in 2012-15.