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).
Dalton was more common in the past and has since settled at a lower, steady level. All-time it's been given to 86,142 U.S. babies, the 911th most common name by sound today, peaking at 4,590 in 1998, with 705 in 2025.
Dalton has no common alternate spellings by sound.