This one's always a bit of a pain to do a cool graph with, but here's a graph of unique visitors by month:
Basically, we've had 743k unique visitors this year compared to 644k in 2011 and 613k in 2010 (no data before that). So, you can probably at least partially say that SOC was at least partial responsible for about a 15% jump in the number of people who see this site this year.