Updated May 15, 2014 3:38 p.m.: The article was updated to clarify that CDC estimates for nonfatal, violent gun injuries ‘include only injuries caused by violent assault, not accidents, self-inflicted injuries, or shootings by police.”

How many Americans have been shot over the past 10 years? No one really knows. We don’t even know if the number of people shot annually has gone up or down over that time.

The government’s own numbers seem to conflict. One source of data on shooting victims suggests that gun-related violence has been declining for years, while another government estimate actually shows an increase in the number of people who have been shot. Each estimate is based on limited, incomplete data. Not even the FBI tracks the total number of nonfatal gunshot wounds.

“We know how many people die, but not how many are injured and survive,” said Dr. Demetrios Demetriades, a Los Angeles trauma surgeon who has been studying nationwide gunshot injury trends.

While the number of gun murders has decreased in recent years, there’s debate over whether this reflects a drop in the total number of shootings, or an improvement in how many lives emergency room doctors can save.

Doctors and researchers have been advocating for better […]