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).
Rocco climbed for decades and has been a steadily popular name ever since. All-time it's been given to 31,684 U.S. babies, the 926th most common name by sound today, peaking at 785 in 2009, with 679 in 2025.
Rocco has no common alternate spellings by sound.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).