The economy of the GCC contains the economies of the six member states of the GCC. Between 2001 and 2006, the GCC economy has more than doubled in size in nominal dollar terms to about $723bn, according to the Institute of International Finance (IIF), making it the world's 17th biggest economy. Burgeoning state revenues fuelled by soaring oil and gas prices are significant but not the only factor underpinning booming economies in recent years. There are encouraging signs that the energy-rich region is actually deploying surplus petrodollars (windfalls) to more prudent use--unlike the spending binge of the 1970s and early 1980s. Moody's Investors Services, the global credit-rating agency, commented: "A higher proportion of [oil revenues] has been saved than previously, while extra government expenditure has been focused more on capital than on current spending. Most governments are also proceeding with structural reforms aimed at boosting the private sector."