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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).
Jeffrey
Jeffrey has been slowly declining from its former popularity. All-time it's been given to 1,288,834 U.S. babies, the 787th most common name by sound today, peaking at 44,340 in 1962, with 700 in 2025.
By sound, Jeffrey also includes the spellings Jeffery, Geoffrey, Jeffry, Jefferey.
Rising