Some interesting facts here:
1 in every 25 Americans is named Smith, Johnson, Williams, Brown, Jones, Miller or Davis . . . In 1984, according to the Social Security Administration, nearly 3.4 million Smiths lived in the United States. . . . By 2000, the Smith population had declined to fewer than 2.4 million.
Also there's a list of the 5000 most common last names in America.
Why would the number of Smiths decline in absolute (rather than relative) terms? Are the Smiths changing their names? (That's a lot of de-Anglicized names, if that's what's going on.) Or do Smiths have an unusually low birthrate? That's 1 million lost Smiths in 16 years, a pretty substantial loss.
Here by contrast are the top ten most common last names among San Francisco Bay Area Home Buyers (2002): Nguyen, Lee, Smith, Wong, Garcia, Tran, Johnson, Chen, Rodriguez, Lopez
http://www.dqnews.com/Web-Site-Extras/WXNames0208.aspx
> Smiths
Legacy of the Iron Age
Now -- if we still took surnames from occupations --- what would the common names be?