This question doesn't really have an answer. The reason is that salary depends on where you are located in the country, what type of job it is (medical or school, etc), what level of education and certification you have, whether you are working freelance or for an agency, whether it is platform interpreting or VRS interpreting or 1-on-1 interpreting, etc. There are just too many variables to say exactly what the salary would be.
For example, an interpreter in a court in Washington DC who has full certification (including legal specialist certification) might make $100+ per hour. An elementary school interpreter in Arkansas with no certification might make $15 per hour. And there are all kinds of ranges in between.
It's impossible to provide an accurate answer because it varies so much. 
