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Brilliant. Extremely relevant and accurate. Many thanks also goes to
tan-ga and demeritcowboy-ga.

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Excellent answer!  Thanks so much for the insightful info!

Great job. I was going nuts trying to find this number. I got the
number I wanted plus a great web address with more info. Thank you!!

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Although I got more specific information from the user comments, I'm
pretty satisfied, as I did get my answer after all.

Thanks. The links to www.literacytrust.org.uk are very useful. Not
sure why I couldn't find that myself!

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Thanks for the answer and great additional information.

An excellent treatment of a complicated question, thoroughly documented.

Thank you.

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Hello tehuti,

Thanks for your efforts.  (I tried that online median calculator you
suggested, and it does work with my ipaq ia-2 internet appliance, but
it would be laborious punching all those numbers in.)

Very happy with answer considering the complexity of an obscure
subject and answered within an hour! You have saved me many hours of
looking on the net and got to more specific help than I did. Many
thanks.

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It's too bad there isn't more information about the puzzle-writing
process.  The software is interesting, though.

partial answer