Prices for some natural resources are subject to wide fluctuation: for example, crude oil prices rose from around $3 per barrel to $12/bbl in 1974 following the 1973 oil crisis and fell from $27/bbl to below $10/bbl during the 1986 glut. In the decade from 1998 to 2008, it rose from $10/bbl to $145/bbl, before falling by more than half to $60/bbl over a few months. When government revenues are dominated by inflows from natural resources (for example, 99.3% of Angola's exports came from just oil and diamonds in 2005), this volatility can play havoc with government planning and debt service. Abrupt changes in economic realities that result from this often provoke widespread breaking of contracts or curtailment of social programs, eroding the rule of law and popular support. Responsible use of financial hedges can mitigate this risk to some extent.