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).
Sarah was more common in the past and has since settled at a lower, steady level. All-time it's been given to 1,539,279 U.S. babies, the 162nd most common name by sound today, peaking at 39,999 in 1982, with 4,278 in 2025.
By sound, Sarah also includes the spellings Sara.