The dollar is heading for its best annual performance in nearly a decade as a strengthening U.S. economy dampens expectations for a Federal Reserve rate-cutting cycle, while President-elect Donald Trump's threat of strict tariffs supports bullish bets on the dollar. The Bloomberg Dollar Index has risen more than 7% so far this year, marking its best performance since 2015. As other central banks have had to step in to support their national economies, all developed country currencies have weakened against the dollar.