I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "According to heraldic sources 1,600 is a total estimated number of all legal ennoblements throughout the history of Kingdom of Poland and Polish-Lithuanian Commonwealth from the 14th century onward (half of which were performed in the final years of the late 18th century)."? 

What suggests it took 400 years for the first 800 ennoblements?