If you decide to search for data on your own, add the word "data" or "statistics" to your search. If you need a phrase, use quotes around that phrase. Pay particular attention to the who is producing the data and use the guidelines for evaluation.
There is a lot of data out there, some of it easily findable and freely available via search engines, such as Google. Does that mean you can't use it? Not necessarily. Ask yourself a few questions to evaluate the data. You might also want to use the SIFT Method to help evaulate.
Below are some categories of who and why.
If the data you find helps answer your question, make a point and it meets one of the criteria above, it should be OK to use. When in doubt, ask your professor!