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).
Adan
Adan has stayed fairly steady in American naming for generations. All-time it's been given to 31,624 U.S. babies, the 893rd most common name by sound today, peaking at 1,164 in 2005, with 631 in 2025.
Adan has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).