Digital radio continues to struggle in the U.S., with few listeners being willing to pay for the subscription-based service, even to get hundreds of stations featuring a much wider range of music and talk than can be found on traditional radio. But in the U.K., digital radio seems to be taking off. Many radio stations have introduced digital incarnations of themselves, and the BBC has added several new digital-only networks, and listeners appear to be responding, especially since low-cost sets became available last year. 155,000 digital sets are known to have been sold, and estimates have that number growing to a million by the end of 2004.