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).
Matthew is down from its peak but still widely used. All-time it's been given to 1,737,400 U.S. babies, the 65th most common name by sound today, peaking at 52,402 in 1983, with 7,243 in 2025.
By sound, Matthew also includes the spellings Mathew.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).