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).
Peter
Peter is now well below its former popularity. All-time it's been given to 591,531 U.S. babies, the 416th most common name by sound today, peaking at 11,628 in 1957, with 1,954 in 2025.
Peter has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).