Source: U.S. Social Security Administration national baby-name statistics.
https://www.ssa.gov/oact/babynames/limits.html
Aggregated first-name counts only; names occurring fewer than five times per geographic area/year are suppressed by the publisher.
U.S. federal government work: public domain in the United States under 17 USC 105.
https://www.copyright.gov/title17/92chap1.html#105
This derivative keeps only generic first names, ranked across the published annual files, without person-level records or credentials.