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).
Jack
Jack has climbed over the years and is holding near its high. All-time it's been given to 759,677 U.S. babies, the 37th most common name by sound today, peaking at 12,884 in 1927, with 8,754 in 2025.
Jack has no common alternate spellings by sound. Spellings sometimes heard the same way: Jacque.
Rising