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).
Charles was more common in the past and has since settled at a lower, steady level. All-time it's been given to 2,447,135 U.S. babies, the 109th most common name by sound today, peaking at 40,919 in 1947, with 5,908 in 2025.
Charles has no common alternate spellings by sound.