I'm surprised at Winston and Franklin - I'm pretty confident that the bump/spike was due to Churchill and Roosevelt. Barack unfortunately was not in the list, so we can't compare that. But compare that to Joseph (Stalin), also a common name, which didn't experience a dip. But then again, neither did Adolph.
Is there a name that experienced a dip, and then became popular again, due to a significant person?
Is there a name that experienced a dip, and then became popular again, due to a significant person?