Australians study the most

Just to point out, this table is from the year 2005, maybe there is a more updated table?  Also, I studied for a semester in university in Sydney, Australia and the level of education there was something I had never seen before.  I grew up in Florida and went to University in Washington DC (George Washington University).  The students were 10x more serious than any students I came across in America, much better at time-management, much more intelligent, motivated and driven.  This I'm sure has a lot to do with the university success rate in Australia.  Many people are successful there and people love their lives.  It's a very nice place. 

Higher education & econ. growth

I am not an economist, so I can only give you anecdotal information. I taught in Australia for four months and I certainly had the impression that students there were more serious about study and learning than those in the U.S. I do not know how students are selected for college in Australia, but that could have something to with it. also, I do not know how students pay for higher education. That could also have an effect.  In the U.S., if you have a pulse, you can get into some school somewhere. Regarding your specific question, I have attached a link to a book on that very subject. Anecdotally again, I do not know of a country that is well developed and does not have a hgher education system. 

yeah I think so, most of the "study in abroad" percentage goes to Australia, here is one the australia's universty sites Study Abroad Australia