Bytes/Character

Python 3, 42 36 bytes

lambda x:[len(i.encode())for i in x]

APL, 15 chars

≢¨'UTF-8'∘⎕ucs¨

In English: convert each character to UTF-8 (meaning: vector of bytes representation) and get its tally.

C, 68 65 bytes

b;main(c){for(;~c;b=c/64^2?b?putchar(b+48)/48:1:b+1)c=getchar();}

Thanks to @FryAmTheEggman for golfing off 3 bytes!

Test it on Ideone.