Among the reams of data the U.S. Census Bureau collects and generates from the national census is a list of the most popular names in the United States. Now you can find out just how common your name is. That even includes your first name since there are three listings available: by surname, by male first name and by female first name.
I checked and found that EASTMAN is the 1,661st most popular name in the United States out of the 88,799 surnames listed. I also checked my first name for popularity. You can do this too at: http://www.census.gov/genealogy/www/freqnames.html