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).
Apollo
Apollo has been climbing in recent years. All-time it's been given to 9,012 U.S. babies, the 810th most common name by sound today, peaking at 820 in 2022, with 708 in 2025.
Apollo has no common alternate spellings by sound.
Rising
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).