The surge did not last long due to the near collapse of the world economy towards the end of the same year, 2008. The main measure of the Australian dollar compared to other currencies is the Trade Weighted Index (TWI) weighted by the importance of trade flows in Australia. However, the fluctuations of the Australian dollar against the US dollar are greater than the WTI. The reason is that TWI only focuses on the rise and fall of the Australian dollar. Trade: Exports and ImportsWhen talking about exports and imports, an economist views trade balances as a measure of any government's economic health and relationship with its trading partners. The main concern is the trade deficit, which is the current currency value of exports minus the current currency value of imports. On average, trade should make up a quarter of any country's economic activities. However, this is not practical for many economies, including the United States, due to their enormous demand for goods. Although trade is the exchange of goods and services, this exchange plays a key role in an economy. To have good trade between countries, there must be adequate trade and investment policies