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).
Lucian has been climbing in recent years. All-time it's been given to 24,499 U.S. babies, the 742nd most common name by sound today, peaking at 935 in 2025, with 935 in 2025.
By sound, Lucian also includes the spellings Lucien.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).