Hi!

I'm trying to determine the number of distinct classes that have
graduated from High School in the US, by year for the last 50 years.

I have the number of graduates by year (see other questions that I've
asked) and I have the number of High Schools in the US for 2000.  This
tells me that in 2000, there were an average of 77 graduates per high
school.  However, I don't think that this holds historically.  I'm
sure the baby boom affected these numbers.

I think that I need the number of High Schools in the US each year for
the last 50 years in order to do this.

Help!?

Thanks!