I saw a tweet to this article with a fact I found astounding, "Last year, the British police in total fired their weapons fewer times than Darren Wilson did on August 9th."
The full Economist article, Armed police: Trigger happy, is behind a paywall (though I think you can get free access to three articles per month). It has a few more details and puts the statistic into a little more context. Here's the relevant parts:
"The shooting of Michael Brown, an 18-year-old African-American, by a police officer in Ferguson, Missouri, is a reminder that civilians—innocent or guilty—are far more likely to be shot by police in America than in any other rich country. In 2012, according to data compiled by the FBI, 410 Americans were ‘justifiably’ killed by police—409 with guns. "
"Last year, in total, British police officers actually fired their weapons three times. The number of people fatally shot was zero. In 2012 the figure was just one. Even after adjusting for the smaller size of Britain’s population, British citizens are around 100 times less likely to be shot by a police officer than Americans."
"The explanation for this gap is simple. In Britain, guns are rare. Only specialist firearms officers carry them; and criminals rarely have access to them. The last time a British police officer was killed by a firearm on duty was in 2012, in a brutal case in Manchester. The annual number of murders by shooting is typically less than 50."
"In America, by contrast, it is hardly surprising that cops resort to their weapons more frequently. In 2013, 30 cops were shot and killed—just a fraction of the 9,000 or so murders using guns that happen each year. Add to that a hyper-militarised police culture and a deep history of racial strife and you have the reason why so many civilians are shot by police officers. Unless America can either reduce its colossal gun ownership rates or fix its deep social problems, shootings of civilians by police—justified or not—seem sure to continue."