How much is too much to spend on travel?

I spent this morning reviewing my finances on my favorite (and free!) financial tool Mint.  Unfortunately I was made painfully aware of something I had always known but never quantified -- I spend a lot of money on traveling. 

Last year I spent 12% of my income on travel.  As a comparison, I spent 30% on my mortgage and 5% on food and utilities each.  I also sock away the financially advised 10% of my income in my 401K and savings.  So is 12% of income on my 'hobby' too much?

Would love your comments here.