How to read the band →
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).
Dexter
Dexter is now well below its former popularity. All-time it's been given to 36,800 U.S. babies, the 1,249th most common name by sound today, peaking at 842 in 2012, with 393 in 2025.
Dexter has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).