What percent of US citizens are agnostic?

In 2012, the Pew Research Center conducted a study, concluding that six percent (6%) of the population within the United States claimed to be either Agnostic or Atheist. The accompanying graph, which can be found on the link below (reference page 9 of the study), would indicate that approximately half of those polled would fall into the "Agnostic" catagory.

Thus, it can be safely concluded that approximately 3% of the population actively identifies with being Agnostic.

The study can be found at the following location:

http://www.pewforum.org/uploadedFiles/Topics/Religious_Affiliation/Unaffiliated/NonesOnTheRise-full.pdf