According to my rough calculations, in 1901 there were around 254,230 baby girls' births registered in the US. Of those, 13,136 or a whopping 5.167% were named
Mary. Another 2% were named
Helen, and the next 7 names (
Anna,
Margaret,
Ruth,
Elizabeth,
Marie,
Florence and
Ethel) accounted for another 10.2% combined.
The result of this very heavy weighting towards the top few names is that names with quite small usages, like
Barbara, get pulled further up the rankings.
https://nanowrimo.org/participants/christine-seaforth-finch
http://christineseaforthfinch.blogspot.com/