According to a new report from market research firm The NPD Group.

21.3 million “PC Game full-game digital downloads” were purchased in the USA in 2009 while 23.5 million physical units were bought at retail during the year, according to NPD’s figures. DD raked in 48% of unit sales and 36% of dollar sales.

The group also offers its own ranking of the various digital distributors, divided into categories of “casual digital retailers” and those “which often focus on titles that are also offered in retail stores as physical purchases.” The ranking supports Direct2Drive’s refutation of Impulse’s claim that it held second place in the PC DD market, at least.

Top 5 Frontline Digital Retailers – 2009 (based on unit % share)

  1. Steampowered.com
  2. Direct2Drive.com
  3. Blizzard.com
  4. EA.com
  5. Worldofwarcraft.com

Top 5 Casual Digital Retailers – 2009 (based on unit % share)

  1. Bigfishgames.com
  2. Pogo.com
  3. Gamehouse.com
  4. iWin.com
  5. Realarcade.com