voter registration data Colorado "2014 Voter Registration Statistics" Colorado 53 percent SOS site Colorado end-of-month voter registration 53 percent Colorado Secretary of State Voter Registration Statistics 53 percent end-of-month voter registration "2015 Voter Registration Statistics" As of October 1, 2011 SOS figure "2014 Voter Registration Statistics" "2014 Voter Registration Statistics" "2015 Voter Registration Statistics"