Against the backdrop of rising concern about the cost of energy, most homeowners across the nation are anxiously watching the dropping temperatures as fall advances. Most homes in the U.S. have central heating, and six-out-of-10 have a warm-air furnace. By far the most popular heating fuel is gas — either piped in or bottled — which heats just over 60 percent of the nation’s homes. About one-third use electricity. Fuel oil, while still important in New England, is used to heat just under 8 percent of U.S. homes. And coal and wood, which used to heat a majority of houses, now combine to provide warmth to less than 2 percent of homes. You can find more facts about America’s people, places and economy from the American Community Survey at <www.census.gov>.