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 419,715 U.S. babies, the 51st most common name by sound today, peaking at 11,871 in 2011, with 8,348 in 2025.
By sound, Lily also includes the spellings Lillie, Lilly, Lilli.