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).
Pierce
Pierce has stayed fairly steady in American naming for generations. All-time it's been given to 20,634 U.S. babies, the 966th most common name by sound today, peaking at 668 in 2015, with 618 in 2025.
Pierce has no common alternate spellings by sound.
Rising