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).
Rosemary has been climbing back after years of decline. All-time it's been given to 163,523 U.S. babies, the 641st most common name by sound today, peaking at 4,542 in 1947, with 1,222 in 2025.
Rosemary has no common alternate spellings by sound. Spellings sometimes heard the same way: Rosemarie.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).