How to read the band →
Solid line = floor (spellings that unambiguously belong to the group). Shaded band up to the dashed edge = ceiling (the most it could reach if every ambiguous spelling counted here).
Billy
Billy was more common in the past and has since settled at a lower, steady level. All-time it's been given to 528,437 U.S. babies, the 961st most common name by sound today, peaking at 14,327 in 1930, with 639 in 2025.
By sound, Billy also includes the spellings Billie, Billye.
Rising