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).
Anastasia has been climbing in recent years. All-time it's been given to 57,163 U.S. babies, the 427th most common name by sound today, peaking at 1,905 in 2018, with 1,832 in 2025.
Anastasia has no common alternate spellings by sound.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).