What is your percentile rank if you have an ACT of 24?
I assume you are referring to the composite score.
I searched Google under the key words "ACT composite percentile" to get these possible sources:
http://www.google.com/search?client=safari&rls=en&q=ACT+composite+percentile&ie=UTF-8&oe=UTF-8
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.