context: In the United States presidential election in New Jersey, 2012, Democrat Barack Obama received 14,640 votes (93.3% vs. 66.0% countywide), ahead of Republican Mitt Romney with 909 votes (5.8% vs. 32.3%) and other candidates with 46 votes (0.3% vs. 0.8%), among the 15,683 ballots cast by the citys 22,555 registered voters, for a turnout of 69.5% (vs. 68.8% in Union County). In the United States presidential election in New Jersey, 2008, Democrat Barack Obama received 15,280 votes (92.3% vs. 63.1% countywide), ahead of Republican John McCain with 1,110 votes (6.7% vs. 35.2%) and other candidates with 56 votes (0.3% vs. 0.9%), among the 16,548 ballots cast by the citys 22,516 registered voters, for a turnout of 73.5% (vs. 74.7% in Union County). In the United States presidential election in New Jersey, 2004, Democrat John Kerry received 11,508 votes (85.4% vs. 58.3% countywide), ahead of Republican George W. Bush with 1,773 votes (13.2% vs. 40.3%) and other candidates with 88 votes (0.7% vs. 0.7%), among the 13,480 ballots cast by the citys 20,445 registered voters, for a turnout of 65.9% (vs. 72.3% in the whole county).
question: How many registered voters did not vote in 2012?
answer: 6872