It's about 0.0000008 times the number of Chickens in the World.
In other words, 15,000 is 0.000000790 times the count of Chickens in the World, and the count of Chickens in the World is 1,300,000 times that amount.(a.k.a. fowl) (Gallus gallus domesticus) (2011 figures) (average population)
The most numerous domesticated animals in the world, the estimated average population of chickens worldwide is 19 billion animals. Of these, about 6.4 billion birds produce the world's supply of chicken eggs.
It's about 0.00000005 times the number of Emails Sent per Day.
In other words, 15,000 is 0.0000000510 times the count of Emails Sent per Day, and the count of Emails Sent per Day is 19,600,000 times that amount.(2010 figures) (estimated averages)