Given is bar chart compares
Given is bar chart comparing
A more detailed ( no comma here) look at the graph shows
New Brunsick, Nova Scotia, Quebec, and Alberta (there were around 7%, 6.5%, 6.1% and 5.7%
Ontario, Newfoundland and Labrador, Manitoba, and British Columbia (there were just approximately 3.2%, 3.5%, 3.6% and 4.9%
This is called "shopping list" writing, which means just listing obvious figures one after another. Were I you, I tried to identify key trends and compare and contrast patterns.
a significant increase.
the number of Alberta's students which was decreased
A number of Alberta's students were/ are
The number of Alberta's students was/is
Graduation here is uncountable.
Overall, all the colleges show a significant improvement in the numbers of overseas students from 2001 to 2006.
This is a very good example of an overview. What Dumi says above is true. An overview, the important feature in IELTS visual writing, is a short description of a situation that gives the main ideas without explaining all the details.