When you're a kid, a year seems like forever. Appending "and a half" to an age seems significant and necessary. But as you get older, the years seem shorter. Heck, I can't even remember how old I am half the time. Maximilian Kiener uses an interactive timeline to argue why this is. The more years you're alive, the lower the percentage a year actually is of your life. And eventually, one year is just a tiny sliver.