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).
Josiah has climbed over the years and is holding near its high. All-time it's been given to 168,234 U.S. babies, the 83rd most common name by sound today, peaking at 8,094 in 2017, with 6,569 in 2025.
By sound, Josiah also includes the spellings Jasiah, Jesiah, Jessiah, Josiyah.