I strongly suspect the interactive (mostly adult) services were the bulk of the bandwidth; the rest of it was relatively short, infrequent and low-bandwidth ses

I strongly suspect the interactive (mostly adult) services were the bulk of the bandwidth; the rest of it was relatively short, infrequent and low-bandwidth sessions like looking up phone numbers, catalogue ordering or paying the odd bill. There's some info in the Wikipedia article (https://en.wikipedia.org/wiki/Minitel#Finances https://en.wikipedia.org/wiki/Minitel#Finances) about usage and finance which quotes revenues of over $1bn p.a. in 1998. I'd guess that while interest in sex hasn't changed, it does seem the bulk of bandwidth on Minitel went on online chat (erotic/flirting) - likely much more so as a proportion of the total than on the modern internet. I recall Paris (and the Metro in particular) at that time being plastered with (mostly-pink) adverts for 3615 chat services (the Minitel equivalent of a URL).