Not sure how accurate this is going to be. The most common blood type by far is type O, so it stands to reason that a greater proportion of low carbers will also be type O.
I also don't put much merit with the blood type theory since this has been discussed before and some people with blood types other than O have done quite well with low carb. As ItsTheWooo already pointed out, very few (if any) people are "pure" blood types with genetic influences from a wide variety of blood types and ancestors. Each time two people have a child, that child not only has a unique mix of the two parents' genes, but the genes of each parents ancestors as well.