Considering all adults over the age of 22 living in the US today, what
is the average education level of these people??  This should be
something like, average is completed 12th grade, or completed 12th
grade plus one year of college, or completed 6th grade, or whatever
the answer is.

U.S. Census Bureau information highlights education levels by race,
sex and age.   Using a statistical technique called interval analysis,
allows us to answer your question for people 18-and-older and people
25-and-older.

For people 18-and-older, the average education level of those 194
million Americans is: 13.06 years or just over one year of college
For people 25-and-older, the average education level of 169 million
Americans is: 13.12 years or just over one year of college

The numbers are so close because of the high percentage of 18-24 year
olds who are completing high school and going on to college.  (It's
pretty safe to say that the same average applies to people over 22!)

Interval analysis requires an estimation of the number of years of
education in some cases.  Thus, completion of elementary school is 8
years and completion of high school is 12 years -- but we have to
estimate a number for "some high school."  In this case, it's 10
years.

We're also forced to eliminate multiple degrees, which would add to
years of education.

The census report on which this is based is "Educational Attainment
Level By Sex, Race and Ethnicity, and Age, 1996" (Internet release:
April 10, 2001):
http://www.census.gov/population/socdemo/education/p70-72/tab01a.txt

A great question fwscholl -- and  the answer contains a surprise too!

Best regards,

Omnivorous-GA

Answer was good and supplied promtly;  just what I needed!  Thank you,
I'll try this service again.

Thanks for your kind comments fwscholl!  I was so surprised that the
Census-supplied data provided little difference between the 25+ and
18+ age ranges that I triple checked the data and calculations.  When
you see the high percentage of people of retirement age who didn't
complete elementary school, let alone go beyond high school the data
start to make sense.

Thanks again,

Omnivorous