I believe that, starting this year with episode 1, each subsequent year will see the next movie released in 3D, leading up to the 40th anniversary (2017) which will be episode 6 in 3D.
Could be wrong, but:
2012 -Episode 1, 2013 - Episode 2, 2014 - Episode 3, 2015 - Episode 4, 2016 - Episode 5...