> There are still today linguistic communities without writing, although they're becoming much rarer.

From a 1969 study of preindustrial societies (though I'm not sure if they are all contemporary or if some are historical):

    39.2%: No writing
    37.1%: Pictures only
    23.7%: Writing

It's from a somewhat famous data set in its field: George P. Murdock, D.R. White. Standard Cross-Cultural Sample (SCCS). Ethnology (1969)