On May 5, 2016, CMS released the third annual set of data files on physician and laboratory behavior: comprehensive multi hundred megabyte data sets of CPT codes and who used them and where.
For the CMS press release, here. For a short article at HealthcareDive, here. For the actual data set page (where you can find 2012, 2013, 2014 in sequence), at CMS, here.
For a short blog on the data set, here.