According to the federal government, the United States' reliance on coal for electricity is decreasing. The percentage of America’s power generated by coal fell to a 30-year low at the beginning of this year.A report from the Energy Information Administration found that coal’s role in the country’s power mix is declining. Coal generated 46 percent of the nation’s energy during the first three months of 2011—a full three percentage points lower than the same period last year.This is the lowest percentage of electricity generated by coal that America has seen in three decades. One of the reasons for the decline could be an increase in natural gas use. As coal prices rise, natural gas prices have remained comparatively low.Though the data isn’t finalized, the EIA says preliminary data suggests that coal made up slightly more of the nation’s energy during the second quarter of this year, partly because there were nuclear power plant outages this spring.