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).
Finnegan
Finnegan has held a fairly steady level of use. All-time it's been given to 13,115 U.S. babies, the 924th most common name by sound today, peaking at 865 in 2021, with 575 in 2025.
Finnegan has no common alternate spellings by sound.
Rising