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).
Margaret is now well below its former popularity. All-time it's been given to 1,289,684 U.S. babies, the 340th most common name by sound today, peaking at 29,038 in 1921, with 2,476 in 2025.
By sound, Margaret also includes the spellings Margret, Margarette, Margarett.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).