I have no data but feel that boys tend to get the family names and biblical names (in US anyways). It's rare to hear of a girl named Elizabeth III or Mary Junior but quite common for those concepts in boys. So I think the boy names are heavily weighted on probably the most popular ~25 or so names. Since girl names are more free to follow whatever is fashionable at the time, trends move faster.
My son is named after his grandfather, and it's an overly common name in English (American and British). Definitely a top 3 most common for last several centuries
My son is named after his grandfather, and it's an overly common name in English (American and British). Definitely a top 3 most common for last several centuries