As the German magazine "duz -- Unabhängige Deutsche Universitätszeitung" asked me about some statement on "demographic change and universities" in the Icelandic context, I investigated the number of students vs. the number of faculty members (=sum of different levels of professors) in Iceland (and Germany for comparison). Only a fracture of my data will get published in "duz", so here is the full data (based on data from Statice and Destatis -- data for 2012 not yet available):

       Iceland                                          Germany
Year  #Students Change  #Faculty Students/Faculty      #Students Change
2005    16 074             623    25.8                 1 985 765
2006    16 835   +4.73%    682    24.7                 1 979 043  -0,3%
2007    16 851   +0.09%    708    23.8                 1 941 405  -1,9%
2008    17 165   +1.86%    761    22.6                 2 025 307  +4,3%
2009    18 291   +6.55%    833    22.0                 2 121 178  +4,7%
2010    19 159   +4.74%    807    23.7                 2 217 294  +4,5%
2011    19 334   +0.91%    790    24.5                 2 380 974  +7,4%

The explanation for the 2009 and 2010 increase of Icelandic students is the economic crisis in Iceland 2008 that did lead to a high number of students starting to attend university.
As you can see, the student/professor ratio got worse after the crisis in Iceland (due to students flooding the Universities and reduction in the number of faculty members due to decreased funding). For Germany, I did not calculate that ratio for all years, but just for 2011, together with more detailed further data for both Iceland and Germany (note that the number of students in Germany 2011 in the table below is different than in the table above: the above time series is from a different Destatis source than the numbers below):

2011                       Iceland     Germany
Enrolled students          19 334    2 501 990
Population                318 452   81 843 743
Students/Population            6%           3%

Prófessorar  316  Professoren           42 924
Dósentar     213  Dozenten & Assistenten 3 899
Lektorar     261					
Sum faculty members 790                 46 823

Faculty members/Population  0.248%      0.057%
Students/Faculty member      24.47       53.44

OECD collects data on governmental or public spending for tertiary eduction divided by GDP -- however, I could not find this data on the OECD statistics web page.
P.S.: I just stumbled over a visualisation of academic brain drain that uses this GDP ratio (from World Bank) as well as one input parameter of their polymetric visualisation.
P.P.S.: A related visualisation is on the number of researchers per inhabitants. However, the data there is from before the 2008 economic crisis.
P.P.P.S.: Here is finally the OECD data from Education at a Glance 2015 (DOI:10.1787/eag-2015-en).