Each year is, on average, 365.25 days (with two places of precision).
So, if uniformly distributed, today is the birthday of 1/365.25 of the population!
I wouldn't say 4/1461, because 1. We lose the fact that we're dealing with an imprecise number, and 2. It's harder to see that and tie it to the fact that a year is about 365.25 days long.
I will travel back in time and fight my elementary school math teachers now.