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).
Ethan is down from its peak but still widely used. All-time it's been given to 500,756 U.S. babies, the 26th most common name by sound today, peaking at 22,566 in 2004, with 11,512 in 2025.
By sound, Ethan also includes the spellings Eithan, Ethen.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).