Hardware industry surveys claim levers account for 15 percent of door-opener sales for U.S. homes and that number doubles when it comes to the high-end market, McClatchy Newspapers reported Thursday.

"For us, in the high end or medium, it's always levers now," said Mary-Lynn Hall, a project designer at Phoenix's EXPO Design Center, an upscale offshoot of Home Depot.

The popularity of levers in the commercial market was bolstered by the Americans with Disabilities Act, which requires doors to public buildings to be "usable with one hand, without tightly grasping, pinching or twisting of the wrist."

That rule led many hotels, restaurants, stores, hospitals, nursing homes, condominiums, airports, commercial and government buildings and schools to do away with knobs in favor of more user-friendly levers.