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).
Emmanuel was more common in the past and has since settled at a lower, steady level. All-time it's been given to 152,452 U.S. babies, the 265th most common name by sound today, peaking at 4,446 in 2008, with 2,716 in 2025.
By sound, Emmanuel also includes the spellings Emanuel, Immanuel.