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).
Marvin
Marvin is now well below its former popularity. All-time it's been given to 255,807 U.S. babies, the 1,159th most common name by sound today, peaking at 4,484 in 1928, with 385 in 2025.
Marvin has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).