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).
Julie is now well below its former popularity. All-time it's been given to 519,128 U.S. babies, the 1,244th most common name by sound today, peaking at 18,519 in 1958, with 323 in 2025.
By sound, Julie also includes the spellings Juli.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).