I'm Dating Myself Here...
Gas Prices
The day I got my driver's license: $0.99
The day I graduated college: $1.95
Today: $3.69
It's sad that I remember those prices. But, I remember that the day after I got my driver's license (I was 17 by the way), gas prices crossed the $1.00 mark. And I remember telling my parents to fill up their tanks in Minnesota before going home since it was over $2.00 in Wisconsin. And then today, gas prices dropped $0.10. There are exactly 4 years between each of those gas price dates.
Crazy, huh?