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).
Frankie has been climbing in recent years. All-time it's been given to 82,574 U.S. babies, the 786th most common name by sound today, peaking at 1,235 in 1959, with 842 in 2025.
By sound, Frankie also includes the spellings Franky.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).