Want to Compare Ratings by group of tier's stuck in the process

I have an Excel Spreed Sheet which has  Tiers 1,2 and 3  so on the tiers column i did a countif and got the total of tiers 1,2 and 3 which you can find on the image below.  now i have a rating column next to the tier column which can have 0,1,2,3 and 4 rating.


so now i need to see what the rating was for each tier.

for example in the above picture
there is a total of 4 tier 1's so for a maximum of rating  3 we get 4*3 =12

and in the rating column for the tier 1 we have 1,1,3,3 so that would be 8

i then want to divide 8/12 66.67 % for tier 1 so  how can i create a formula that i can pass into rating column that can do that?

Thanks