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).
Jayce was more common in the past and has since settled at a lower, steady level. All-time it's been given to 47,162 U.S. babies, the 350th most common name by sound today, peaking at 3,191 in 2015, with 2,230 in 2025.
Jayce has no common alternate spellings by sound.