On a related note, what does organic search traffic look like these days? I was once personally invested in running several small content sites and at the time organic traffic was pretty much entirely from Google. There were other inbound sources - Bing, Yahoo!, etc. - but they were so negligible that it would have been reasonable to ignore them completely for the purposes of optimization.

I've been using DDG as my primary search engine now for several years, and using Google no longer "feels like the Web" for me. I imagine I have one hell of a case of observation bias in that, but it does seem like alternatives have been gaining some traction in recent years.