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).
Colt has been slowly declining from its former popularity. All-time it's been given to 30,954 U.S. babies, the 502nd most common name by sound today, peaking at 2,033 in 2019, with 1,317 in 2025.
By sound, Colt also includes the spellings Kolt.