Countif Date given makes them within a certain age range

Hi!

I have a list of birthdays, and I'd like a function that CountIfs the birthdays fall within a certain age range, i.e. 0-8, 9-16, 17-26, etc.

The function needs to be live, so it would have to also be able to countif birthdays tomorrow or a year from now based on a list of birthdays and be able to return a count of their age range breakdowns.

Thank you for your time.

=sumproduct(--(year($e$1:$e$52)<(year(today())-a8)))-sum(b9:$b$21)