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).
Lily was more common in the past and has since settled at a lower, steady level. All-time it's been given to 416,332 U.S. babies, the 53rd most common name by sound today, peaking at 11,716 in 2011, with 8,311 in 2025.
By sound, Lily also includes the spellings Lillie, Lilly.