This single diagram explains the market dynamic year over year in a way I've never seen anywhere else. The 1/3/5/10 yr returns figures you see don't even come close to understanding the nuances of one year over another.
I remember when this diagram was published in 2011 and _still_ refer to it routinely.
This is why you do dollar cost averaging and steadily invest every year, to spread out your investments over multiple years.