The United States is the world’s second-largest producer of natural gas, the third-largest producer of crude oil and the largest importer of oil and natural gas. It also generates more electricity each year than any other country – nearly a quarter of the world’s total. The top five oil companies earned more than $100 billion last year, and top oil executives have appeared before Congress to defend their record profits. Meanwhile, a recent poll showed that 89 percent of Americans believe oil companies deserve a great deal or some of the blame for current energy problems. An intertwined set of domestic and international events have pushed gas prices steadily higher over the past few years, and an almost unquenchable global demand for energy may keep them there for at least the short term, industry observers say.