50 years since I graduated High School?

My wife was mentioning to me that next year will be 50 years since I graduated High School in May of 1966 in Santa Fe, New Mexico. This doesn't seem possible. I had been mentioning how a movie I was looking at a little called "Stagecoach" just now was made in 1986 and how that was already 30 years ago. That just doesn't seem right. It seems like 1986 should be 10 or 20 years ago and 1966 should only be 30 years ago at most but nope already right now if you graduated high school in 1965 the year before me you are now in your 50th anniversary of either High School or college if you graduated that year.