Z is for Zebra

Courtesy: My Cute Graphics

I'm in word snoot mode today, thinking about why my Q and X keyboard  keys aren't more worn because I am VERY fond of words that begin with those letters and even fonder of words that use both--quincunx, exquisite, quixotic. (If you want to see more words that have both letters, or any other letter combinations, check out Scrabble Wizard.)
I started wondering why Z is the least-used letter. Are there that many fewer words that start with Z?  (I mean sure, that would be the obvious conclusion but what about some facts?) As they say on NPR's marketplace, "let's run the numbers."
There's a  site called words by letter that lets you search words by length, by definition and by suffix and prefix (two words with Xs).
Vocabulary.com will give you interesting factoids like 100 SAT words that begin with W,X,Y & Z. There's only one for X (xenophobia) but seven for Z.  So that's a little counter-intuitive.
Over at TalkTalk where there's a dictionary of difficult words, the Z word list begins with zaibatsu (from the Japanese, meaning a large industrial or financial corporation) and ends with zymotic (defined as: a. pertaining to fermentation; due to development of germs entering body from outside; n. contagious or infectious disease.) I will definitely be back to that site because I love obscure words.
If I still had a paper dictionary, I'd just count the number of pages devoted to Z letters and compare it to the number of pages devoted to E.  Further research must be done!  But not today.