[Lockal]

I think a bit more interesting statistics is to count only \w—\w. This excludes cases like "(—)" and emdashes surrounded by spaces, which is, apparently, what Russian-speaking users like to use. Also it is an very old tradition to format page titles as <title>[Page name] — [Website name]</title>: depending on language this is a default setting for MediaWiki, WordPress, etc.

[n2d4]

Not just Russian speakers put spaces around the emdash, but also the AP style guide.

Also, for what it's worth, UK style guides recommend endash + spaces (but many write emdash + spaces instead), and so do some other languages (eg. German). There are more countries than just America and Russia!

[Lockal]

No, I mean in few Slavic languages emdash is replaces "is a / ist / est / es / ...", therefore you will see it in 99% of ru/be/uk Wikipedia articles *in the first sentence*. Coincidentally, in these languages emdash must be surrounded by spaces (no exceptions).