Oliver Keyes, 19/02/2016 13:51:
a lot of prominent countries were very close to the 50% switchover, including (interestingly) Italy.
I compiled some links at https://meta.wikimedia.org/wiki/Research:The_sudden_decline_of_Italian_Wikip... on the likely social reasons.
Pew research also had some numbers on the matter for USA, recently.
Nemo