Bluebulb Projects' The Measure of Things presents:
25,000 is about one-nine-hundred-fiftieth the number of Books in the US Library of Congress (2013)
In other words, it's 0.0010596783 times the count of Books in the US Library of Congress (2013), and the count of Books in the US Library of Congress (2013) is 943.682630 times that amount.