Percentage of letter in string

We will count the number of occurance of the letter in the string, and then calculate the percentage of the given letter.

class Solution:
    def percentageLetter(self, s: str, letter: str) -> int:
        return int((s.count(letter) / len(s)) * 100)

Time complexity: O(n), n is the length of the string.
Space complexity: O(1)