I found the census figures I mentioned in the earlier post. The report is from 2003 and can be found here. It is from their "Facts for Features" publication and is a back to school issue. These are the main figures:
850,000 --Number of students who are home-schooled. That is 2 percent of all students ages 5 to 17.
10--Percentage of all students who are enrolled in private elementary or private high schools.
53.4 million--The number of students projected to be enrolled in the nation's elementary and high schools (grades K-12) this fall.