LOS ANGELES, Oct 4: British folk band Mumford & Sons scored the biggest debut of the year so far as their sophomore album “Babel” shot to the top of the Billboard 200 album chart on Wednesday, in a year where the U.S. Music industry has been dominated by British imports. “Babel” sold 600,000 copies in its first week of release according to figures from Nielsen SoundScan, almost doubling the sales of Justin Bieber’s “Believe,” which, until now, was the year’s biggest debut with 374,000 units sold in its first week in June. (agencies)