Despite low tax rates, agricultural assistance is the highest among OECD countries and a potential impediment to structural change. Also, health care and education spending have relatively poor returns by OECD measures, though improvements have been made in both areas. The OECD ''Economic Survey of Iceland 2008'' had highlighted Iceland's challenges in currency and macroeconomic policy. There was a currency crisis that started in the spring of 2008, and on 6 October trading in Iceland's banks was suspended as the government battled to save the economy. An assessment by the OECD 2011 determined that Iceland has made progress in many areas, particularly in creating a sustainable fiscal policy and restoring the health of the financial sector; however, challenges remain in making the fishing industry more efficient and sustainable, as well as in improving monetary policy to address inflation. Iceland's public debt has decreased since the economic crisis, and  is the 31st-highest in the world by proportion of national GDP.