There's a built-in function to overwrite your "empty" hard drive space with random data. Problem is it takes forever (and isn't easily accessible). There's a reason why the option isn't available to the average user.

To my understanding, it's because in data sets like these, median is usually closer to what we want. If you had a room with 9 infants and 1 hundred year old person, it's not helpful to say the average age of a person in that room is 10. It's usually more helpful to say the median age is 0, since most people in that room are newborns. Mean is affected by outliers, median is not.

In reality the difference between mean and median for an entire country is minor, but the point is that the median is closer to what we want. Median also gives us a useful data point, the age where half of all people are older than that age, and half are younger. Mean age is less useful.