it'll be parked on the street
45-55% in most countries (France seems like an outlier), but even that is above 20%.
I'd guesstimate that the cars parked "american style" (in a private garage or on the driveway of the house) in Europe is < 10%. You really need to live in a small town or a village to find these setups.
I can see a lot of articles / comments on various portals where the authors are explaining how easy is to use EVs - you charge it in your own garage over night and then drive to office or to do groceries. I can't overstate how unusual use-case it is.
Most people where I live (Switzerland) would never consider using a car to get to work. We walk / cycle / take a bus, tram or train. Same with groceries. The cars are on the street, you use it maybe once every week or two, to go skiing, move something large or go for a longer trip. Average yearly distance per car is ~13'000 km (~8'000 miles). Using an EV is really a huge huge hassle.
Just open google maps, satellite view, and look into any major European city. Given the known ~70% urbanisation of the EU, it seems feasible. From my own, anecdotal experience, I would say way more than most cars are parked outside. Most of the times a block away. Some annoying times, much farther.