The highest overall effective tax rates tend to be in European countries, and the lowest in Australia, New Zealand and the Americas. If well targeted, subsidies can weight incentives in favour of more environmentally sound activities and products, address market failures, and drive green innovation and investment. Governments spent an estimated USD 121 billion on renewable energy subsidies worldwide in 2013 (IEA, 2014a). Mixed messages, "stop-and-go” policy making and retroactive changes can seriously weaken market signals, however. In the United States, only 1 gigawatt of new wind power capacity was installed in 2013 - a fraction of the 13 gigawatts installed in 2012 - following the anticipated expiration of a tax credit on renewable electricity production at the end of 2012 (IEA, 2014a), the credit was subsequently extended in late 2012. Governments currently spend an estimated USD 640 billion a year on environmentally harmful support for fossil fuels, with an estimated USD 550 billion spent by emerging and developing countries.