I graduated/finished/left high school in 2007, so it may well be something that has come into use over the last few years. I also “graduated” primary school in 2002, but that was of course less formal - still, I remember clearly that the word was used.
It seems to me that everyone uses just “graduated” these days rather than “graduated from” so I am surprised (but happy!) to see the latter winning in the poll.
I’ve come across “graduation” used in the context of high schools in New South Wales, Australia. The thing is that high-school graduation ceremonies tend to be held for year-12 students in September, before they sit for the Higher School Certificate examinations in October-November, and there might be another end-of-school ceremony in December on or about the last day of the school year, when the old year-12 students are technically no longer students of the school, and the old year-11 students are now counted as year-12 students. For some reason, year 11 only lasts 3 terms of the 4-term year in NSW.