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).
Emma is down from its peak but still widely used. All-time it's been given to 783,029 U.S. babies, the 7th most common name by sound today, peaking at 22,881 in 2003, with 12,932 in 2025.
By sound, Emma also includes the spellings Ema.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).