Celiac Disease more common now than 50 years ago?

Celiac Disease seems to be increasingly prevalent, and it is now relatively easy to find cafes and restaurants to cater for a gluten-free diet. So is the rise in Celiac Disease due to increased awareness of the condition, or has is actually become more common?

The Mayo Clinic in the US has done a study with frozen blood samples from Air Force recruits in the 1950s. They discovered that Celiac Disease is about 4 times more common now than it was then. In addition, they found that those with undiagnosed Celiac Disease were four times more likely to die than those without. You can read the abstract of the study here.

A big caveat on this: they didn't compare the 1950s Air Force samples with contemporary Air Force samples. They compared them with the general public (although matched for age and sex). I would imagine that Air Force recruits would be in better health than the general populace, and so would be less likely to have Celiac Disease. Sigh, why is it so hard for studies to be done properly?