I have a book with some figures related to that. I can scan in the graphs on Tuesday and post them up here.
For now, here are the number of learners by region (all learners, not just university)
East Asia - 1,375,598
Oceania - 352,923
North America - 134,761
South-East Asia - 132,409
West Europe - 47,451
South & Central America - 30,076
East Europe - 15,085
South Asia - 10,129
Middle & Near East & Africa - 3,671
These figures appear to be from 1998. More to come.