From The Denver Post:

From January to June, 31,518 background checks were processed for concealed-carry permits by the Colorado Bureau of Investigation, according to bureau data. For the same period last year, there were only 16,886 processed.

In addition, more background checks have been processed in the first six months of 2013 than in all of 2011 — and only 1,305 fewer than the total for all of 2012.