According to Comscore, in December 2009, Americans conducted 14.7 billion core searches, with Google Sites accounting for 65.7 percent search market share, virtually unchanged from 65.6 percent in November. Thus Google was searched 9.65 billions times in the US.
Google has noted in their official blog that “Proportion of Google result pages that show a map in search results: 1 in 13″ ( based on our U.S. weekday traffic).
If we do a little back of the envelope calculation and estimate that 85% of searches never leave the front page, we can estimate that the map showed 1.15 times for every 13 front pages shown which means that is shows roughly 9 times per hundred searches.
If any of this is even remotely correct then a map was shown roughly 868 millions times during the month (9%) of December searches. This number is lower than the usual estimates of local searches and as Greg Sterling points out, many searches that show no local intent in fact are.