1. Portugal
Graduation Rate: 96%
Education in Portugal is compulsory until one reaches 18, it is also free. There are many public and private institutions in the country and there are even universities that date back to the 13th century. Not unusual considering Portugal is one of the oldest countries in existence.
There you have it, the list of 10 Countries with the Highest High School Graduation Rates. These countries definitely have great educational systems hence the high graduation rates.