Sorry for the typo in the last message, I was interrupted. What I meant to say was my other two kids will probably also graduate at 15 yrs old. They are currently 14 and 11 1/2 yrs old.
Yes,there is a great book on the statistics of homeschooling. It is called "Homeschooling: The Right Choice!" by Christopher Klicka, Loyal Publishing, www.loyalpublishing.com. Check out Chapt. #5. We have purchased the book for our family a couple of times because we continue to lend it out, but never seems to come back. It may not be the most up to date, but it is a starting point. (P.S. we have been homeschooling since 1996 and have truly been amazed. Our daughter will graduate from high school at 15 yrs. old this year and our other two kids will probably will also.)