Bluebulb Projects' The Measure of Things presents:
15 is about one-and-two-thirds times the number of Symphonies Composed by Beethoven.
In other words, it's 1.666666666670 times the count of Symphonies Composed by Beethoven, and the count of Symphonies Composed by Beethoven is 0.5999999999990 times that amount.
(a.k.a. Ludwig van Beethoven)