I don't really know. I was buying on vinyl in the eighties and started picking up the occasional CD album from around 1988 although I didn't actually bother getting a CD player until 1992. I just bought things when they were too marked down in price to ignore. Think I had around 300 CDs albums before I could even play them at home.
After this I mainly switched format to CD as they were becoming easier to pick up at the right price and often had longer running time that the vinyl equivalents.
To this day, if an album is released on CD I'll usually pick up on that format but I do buy various vinyl albums that don't get a CD issue.
I'd say I have somewhere around 2000 vinyl LPs. Probably around 10000 CDs. I do have things I haven't played in years purely because I haven't got back to them.
I buy 7", 12" and 10" singles too. I like the 7" format and there ar plenty of reissue 45s that I'd quite like but if the A's and B's can be had on compilation CDs I can't justify the expense. What I seem to have almost stopped buying is CD singles.