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).
Gideon climbed for decades and has been a steadily popular name ever since. All-time it's been given to 22,302 U.S. babies, the 643rd most common name by sound today, peaking at 1,161 in 2017, with 993 in 2025.
Gideon has no common alternate spellings by sound.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).