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).
Holland has been climbing in recent years. All-time it's been given to 11,007 U.S. babies, the 910th most common name by sound today, peaking at 686 in 2025, with 686 in 2025.
Holland has no common alternate spellings by sound.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).