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).
Linda was more common in the past and has since settled at a lower, steady level. All-time it's been given to 1,536,997 U.S. babies, the 1,334th most common name by sound today, peaking at 104,758 in 1947, with 324 in 2025.
By sound, Linda also includes the spellings Lynda.