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).
Rosa
Rosa is now well below its former popularity. All-time it's been given to 178,588 U.S. babies, the 1,113th most common name by sound today, peaking at 2,245 in 1925, with 441 in 2025.
Rosa has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).