The American Association of Independent Music (A2IM) exists solely to support independent record labels and includes more than 300 as members. Some of those members, like ABKCO Records, would be right at home in Steve Holland's boxes thanks to catalog releases from Sam Cooke, The Rolling Stones, Bobby Womack, The Animals, Herman's Hermits and others. Others like Bar/None Records, Matador, Kill Rock Stars and Sub-Pop still have a place in Gen X record collections and are still home to artists like Kurt Vile, Iron & Wine, The Thermals , Low and Father John Misty.

As Billboard points out, those indie labels accounted for 32.6% of all music sales last year., up from 32.1% the year before. That's well ahead of the market share held by Warner (14.8%), Sony (22.5%) or Universal (23.9%). A2IM adds that when you look at the digital sales figures, that share jumps to 39%.

They're also growing that market share in ways that would make the little labels among Steve Holland's records envious. Where the steadfast little 45s had to find their way or pay their way into jukeboxes and the hands of dozens to hundreds of DJs across the country, current indie label singles just need to be in an easily accessible digital format. If KEXP plays a Macklemore song in Seattle or WFMU plays the new Cat Power track in New York, streamed broadcasts and ensuing podcasts take them global. Mollie Starr, a representative for streaming music service Pandora, estimates that 70% of the site's catalog comes from independent labels and musicians, with the AAIM reporting that independent labels account for 40% of all Pandora streams.

Similarly, independent singles make up 30% to 35% of the programming on Sirius-XM's satellite radio music channels. As we've said before, terrestrial radio has very little say in what the popular music of the moment sounds like. Increasingly, it sounds like Jack White's 2012 album Blunderbuss, Mumford & Sons' Babel, Vampire Weekend's Modern Vampires of the City and Queens of the Stone Age's ... Like Clockwork -- all indie releases that have topped the Billboard 200 album chart in the last 12 months.

That multi-platform airplay translates to a whole lot of sales when digital distribution brings a song home instantly. Macklemore and Ryan Lewis, for example, can move 500,000 of copies of their album The Heist via Apple's ( AAPL) iTunes, Amazon ( AMZN) or elsewhere without begging Warner, Sony or Universal to help them move product. That's great for artists who go out on their own, but it also does wonders for sales of digital singles, which increased 5.1% last year. It also means great things for digital album sales, which jumped 14.10% in 2012.

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