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).
Jenna
Jenna is now well below its former popularity. All-time it's been given to 148,842 U.S. babies, the 1,128th most common name by sound today, peaking at 6,454 in 1985, with 418 in 2025.
Jenna has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).