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).
Christina has been slowly declining from its former popularity. All-time it's been given to 679,186 U.S. babies, the 883rd most common name by sound today, peaking at 24,323 in 1985, with 598 in 2025.
By sound, Christina also includes the spellings Kristina, Cristina, Krystina, Christena.