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).
Phoebe
Phoebe has been climbing in recent years. All-time it's been given to 43,663 U.S. babies, the 463rd most common name by sound today, peaking at 1,885 in 2025, with 1,885 in 2025.
Phoebe has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).