I doubt there are true statistics. The numbers would be astronomical. Each time a person or bird or pig gets the flu, there is a chance they could be the vehicle for this combination. I don’t think there is any way you could count how many birds have the flu; or pigs either. Each incidence of the flu for people would be difficult enough to quantify.
Thing about statistics is that if there is a possibility, then with enough combinations, it will eventually happen. In case of H1N1, it appears to take about 90 years to provide enough potential combinations.
LOLOL but I can't wait that long! I guess my curiosity will remain unsatisfied. :^)
Thank you so very much for writing, ga medic!