I am white male age 40-45, 6 feet tall, weigh 189 lbs, in good health,
and workout about 3 times per week for 20 minutes aerobics and 10
minutes strength building.  Where do I stand in percentiles in terms
of other men in terms of health and fitness?  For example, am I in top
10, 25, 50, 75% of men of my race and age and how could I measure?

I would suggest that you calculate your BMI (body mass index), which
is a good indicator of your personal health and fitness.

BMI calculators
http://nhlbisupport.com/bmi/
http://www.cdc.gov/nccdphp/dnpa/bmi/calc-bmi.htm

You sound absolutely perfect but how about your eating, drinking &
smoking?

The most important things are 

* not to be overweight

* not to smoke (tobacco or any funny stuff)

* not to drink too much alcohol or caffeine

* not to eat the 'wrong' sort of foods (junk, dairy products, red
meats, etc) -- Go for the low fat stuff

It's how good you feel that matters not where you stand on some
generalised statistical chart.

Go through all the questions at http://www.realage.com/
Some sites have a slimmed down version of the realage test, but the
full quiz will be more accurate.