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).
Christine was more common in the past and has since settled at a lower, steady level. All-time it's been given to 684,683 U.S. babies, the 1,601st most common name by sound today, peaking at 20,355 in 1969, with 225 in 2025.
By sound, Christine also includes the spellings Kristine, Christene, Cristine, Christeen.