actually I‘d also like to know what Twitter participation rates are. My anecdotal idea is that quasi nobody is very online in Europa compared to US. My feeling is in Europa more ppl are on LinkedIn than on Twitter and vice versa in US. Can anyone back this up lol?

There are lots of "very online" EU people that spend time on video games, forums, IRC, reddit, etc.

For example Sweden has a forum flashback.org. I'd argue the swedes are like the most tech literate nation on earth. 

We also crush NA in most video games. I wonder if EU is generally just a bit less focused on career.

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Not sure how not being on Twitter suggests less career focused? Outside of emerging tech Twitter isn’t seen as a place to develop your professional career?

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Aotearoa/New Zealand 

I'm not the biggest user but seems to me like people are making careers through Twitter

You are right. But less than those marking Insta or even FB careers. Twitter is so much smaller still - 15% of FBs monthly active users . Twitter Younger so should be have greater longevity but I don’t see any teens on twitter tho so maybe not