In 2013, it was 69% run success, 52% pass success. This year's numbers aren't there yet, obviously.
(cool search engine for such things:
here)
Changing it to match the situation a bit better (last 2 mins, defense up by 4, 1 yard, 2nd down), 4/4 run plays were successful (100%) vs 8/12 for pass plays (67%). Note that in this kind of situation, NFL teams attempted 12 passes vs 4 runs in 2013 (though the success rates are right there to see). Also note that this is all 1-2 yards to go situations; not just goal line situations.