What do the other 46% do?
So 23.9% are in other parts of academic computer science, mostly Postdocs. another 3.6% go to positions (unspecified) in other academic departments.
His 47% is "North American, Non-Academic, Industry". It doesn't break down research vs. development jobs, which is probably smart.
Another interesting thing is that it's broken down (Table D4) by specialty - so for instance, two PhDs in HCI left the US from the 2010-2011 class, and the specialties with the highest percentage leaving the country after graduating were "Information Systems" and "Networks".