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).
Melanie was more common in the past and has since settled at a lower, steady level. All-time it's been given to 298,867 U.S. babies, the 247th most common name by sound today, peaking at 6,763 in 1972, with 3,112 in 2025.
By sound, Melanie also includes the spellings Melany, Melani, Melonie, Melony, Melaine.