Both fairly wild guesses that I wonder now if they are underestimates. But definitely enough that there are 'some' in more than one location...

I think we went through a phase of thinking 'we don't have a corkscrew/bottle opener, must buy one' several times, and also, people keep leaving them in our house!

My first corkscrew (which I still have somewhere) was attached to my first ever pen knife, which memory insists was a seventh birthday present, though I wonder now if it was actually 8th or 9th...