This table shows the results for the words "vegan" and "vegetarian" on Google since 2004. The blue line represent searches for "vegan". A lot has happened in 6-7 years.

The countries with highest search rate for "vegan" are:
1) USA
2) Canada
3) New Zealand
4) Australia
5) UK

The only place (among these 5) which has more searches for vegan than vegetarian is USA.