US Birth Records (present) Number of male and female births, sex ratio at birth, and number of excess males: United States, 1940–2002.Data Source: Mathews TJ, and Hamilton BE. 2005. Trend analysis of the sex ratio at birth in the United States. National Vital Statistics Reports 53(20):1-17.year: A numeric vector, 1940-2002.boys: A numeric vector, number of male births.girls: A numeric vector, number of female births. CSV Download
