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).
Tiana has stayed fairly steady in American naming for generations. All-time it's been given to 33,701 U.S. babies, the 1,037th most common name by sound today, peaking at 1,206 in 1998, with 516 in 2025.
By sound, Tiana also includes the spellings Tyanna. Spellings sometimes heard the same way: Tianna.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).