Bluebulb Projects' The Measure of Things presents:
13,000 is about 0.00000005 times the number of Emails Sent per Day.
In other words, it's 0.00000004420 times the count of Emails Sent per Day, and the count of Emails Sent per Day is 22,600,000 times that amount.
(2010 figures) (estimated averages)
Each day, human computer users and automated programs send about 294 billion emails. Of those, an estimated 214 billion emails are spam advertisements for pharmaceuticals or drugs.