The mention of "Mabel" got me thinking. And my mother being dissuaded from giving me her favourite name- Emily- because it was too old fashioned and ugly! And reading Sue Perkins' memoir she and her siblings- all in their mid/late 40s are Susan, Michelle and David.
How long before there are Susans, Michelles and Davids again? Another 50 years maybe- so 100 years ish for a cycle?