Tutuzdad-ga, WOW! Thank you for your thorough and thoughtful answer! I
had a feeling there would be no black or white answer to this
question, and you confirmed this with your research. I suppose that in
this case, the courts would probably make a decision the same way you
did in your personal opinion.  IE, if the boss knew his employees did
not like this practice, he shouldn't continue it, particularly if the
business would in no way suffer if he stopped.  You may be interested
to know that I am the employee in question, and I'm the general
manager of the construction company that my dad owns.  So this is a
personal issue as well.  Back when I lived with my parents (I moved
out at age 20, ten years ago) Dad had a similar habit of opening
anything that was sent to HIS address, regardless of the addressee. He
has long known that this is unacceptable to me, but he basically
remains unapologetic. Otherwise, he's a nice guy! I don't plan to take
him to court, but I just bet I'd win if I did. ;-)  Thanks again!

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Thank you so very much to Tutuzdad.  Your research and answer did
exceed my expectations.  Am I allowed to add one more point to ponder
with this scenario?  If so, how?  Thank you so very much!

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Thanks, superb answer.  And quick, too.

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Thanks for the answer. Very informative

Tutuzdad-ga is the MOST diligent and helpful researcher I have EVER
encountered.  He worked and worked so very hard on a near impossible
feat finding an answer for me.  I wish there were more like him.  He
has integrity, high standards for himself and his work and a stick to
it-ness so uncommon to find in this day and age.  I can't say enough
good things about this researcher and I hope to work together again
soon.  Mary Shawn

Excellent, excellent,answers.  Very timely response.  This site is fantastic!

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You are very professionial

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Thank you!! Well done.

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Thank you so very much!!!

Bloody Spectacular - thanks!  This one was haunting me for years
*before* Google was even a concept.

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Thanks so much its  excellent

Excellent answer! You kinda left me hanging at first dangling the
carrot in front of me, so to speak. Then you added some really great
stuff. I am new to Google Answers. Thanks for the info.

Excellent!
Crisp, clean, and an excellent summary.

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Did a great job, exceeded expectations.
Thanks!

Thanks sooooo much, i've got **extremely* and high-quality fast
response! You save me a lot of time ! Really thanks so much!

Thank you so much, Tutuzdad. A job well done. You are a dandy researcher!
And thanks also to pinkfreud and daytrader76 for your comments. I love
Google Answers! See you again soon.

GOODBYE for now.

I appreciate the work and effort.  The references are excellent.  Glad
it was a "fun" question--the whole project on my end is fun too.

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I received 90 percent of what I was looking for. While it wasn't fast,
it seemed like a thorough search.

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Thanks for your answer. Seems like it's as good an answer as I'll get.
justaskscott provided the same answer as a comment five minutes before
you. Maybe in fairness should be rewarded, too. Don't quite know how
to handle this. Any suggestions?
Thanks again.

Thanks Tutuzdad. 
It appears that the Kg cost in (inflation-adjusted) real dollars has
declined over the interval-or at best, stayed level.

Thank you Pink.

Thank-you so much for you clear answers and prompt response

Exceptional information - helped me complete this task in two hours.

Do you want the final term paper?  :)

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well-written and informative, complete answer

Excellent answer!