A year after Facebook launched Open Graph to allow developers to create music apps for the site, the company has offered a selective peak at its progress, showing off some impressive numbers while playing others close to the vest.The big-picture numbers are undoubtedly eye-catching, with Facebook reporting that its users have listened to 62.6 million songs 22 billion times through the site’s apps since September of 2011, making for a cumulative 210,000 total years of music listening. Facebook declined to breakdown what percentages of this listening came from which platforms, however, which makes it difficult to tell how widely this usage is spread across the site’s three dozen or so apps. The company did note that use of apps from heavy-hitters Spotify, iHeartRadio and Deezer has been rising steadily, with the latter tripling its app usage since launching on Facebook. “User adoption has been fantastic,” said Facebook’s manager of strategic partners Ime Archibong. “210,000 hours of music being captured in the whole Facebook ecosystem is really special… And I think there’s plenty of green field left.” Archibong is also quick to tubthump Facebook-assisted growth from some of the lesser known services on the site as well. Streaming service and playlist generator Songza, for example, reported that Facebook-connected users spend 20% longer listening to the site than other users. Indian music distrib Saavn has seen its daily referral traffic from Facebook grow 30 times larger since launching an app.