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).
Frank
Frank is now well below its former popularity. All-time it's been given to 920,589 U.S. babies, the 900th most common name by sound today, peaking at 17,089 in 1918, with 584 in 2025.
Frank has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).