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).
Khalil was more common in the past and has since settled at a lower, steady level. All-time it's been given to 29,491 U.S. babies, the 674th most common name by sound today, peaking at 1,400 in 1995, with 876 in 2025.
By sound, Khalil also includes the spellings Kahlil.