Total and Immigrant Populations, by Age and Sex, for the United States: 2011
When a population pyramid is created, the scale used on the horizontal axis is adjusted to magnify the characteristics of the age-sex distribution for that particular population. This age-sex pyramid places both the total and immigrant populations on the same scale. The age-sex pyramid of the immigrant population takes on a very different shape when it is not adjusted to the total population pyramid's scale.
There were 311.6 million persons in the United States in 2011. Of them, about 40.4 million or 13 percent were immigrants. Total population's male-to-female ratio: 96.8
US Census Bureau, American Community Survey, 2011.