Why is it a bit low? 10% has pretty much been the norm, and food prices have gone up substantially. Again, that's for average or, in most cases, below average service.
I learned that proper dining etiquette was 15% for average service, 20% for good service, and as high as you want for exceptional service.
Like I said, though, it's your money and I'm not going to tell you how to spend it.