Popularity in the United States (by decade)
Numbers
| Cynthia (feminine) | Cynthia (masculine) | |||||
| Year | Rank | Percent Used | Rank | Percent Used | ||
| 2020 | #852 | 0.018 | - | - | ||
| 2010 | #525 | 0.031 | - | - | ||
| 2000 | #220 | 0.075 | - | - | ||
| 1990 | #106 | 0.159 | - | - | ||
| 1980 | #68 | 0.226 | - | - | ||
| 1970 | #31 | 0.487 | #1555 | 0.002 | ||
| 1960 | #10 | 1.040 | #1018 | 0.003 | ||
| 1950 | #11 | 1.335 | #1106 | 0.002 | ||
| 1940 | #47 | 0.390 | #1920 | 0.001 | ||
| 1930 | #191 | 0.088 | - | - | ||
| 1920 | #348 | 0.030 | - | - | ||
| 1910 | #401 | 0.022 | - | - | ||
| 1900 | #404 | 0.022 | - | - | ||
| 1890 | #338 | 0.030 | - | - | ||
| 1880 | #259 | 0.042 | - | - | ||
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