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).
Noel climbed for decades and has been a steadily popular name ever since. All-time it's been given to 111,952 U.S. babies, the 336th most common name by sound today, peaking at 2,451 in 2021, with 2,299 in 2025.
By sound, Noel also includes the spellings Noelle.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).