I found the chart on Eurogamer, but readers there are commenting that it doesn't give a correct view as it only shows the income to Sony, not the income of physical sales to 3rd parties.  So that 3% includes only their own 1st party games of which there haven't been too many, and the cut they take from 3rd party sales.  Physical games apparently constitute 24% of all game sales when you just count the units sold.  

Then again, if that is so, you'd still expect the percent points for physical and digital to be more in a ratio of about 1:3?