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).
Darren has been slowly declining from its former popularity. All-time it's been given to 195,616 U.S. babies, the 1,251st most common name by sound today, peaking at 13,357 in 1965, with 339 in 2025.
By sound, Darren also includes the spellings Darin, Darrin, Daren, Daron, Darron, Daryn.