The stale claim that 40 percent of gun sales lack background checks

The stale claim that 40 percent of gun sales lack background checks - The Washington Post
The letter includes an interesting figure, comparing how many National Institute of Health awards have been given for firearms research versus infectious diseases.

Major NIH research awards and cumulative morbidity for select conditions in the US, 1973–2012
Condition Total cases     NIH research awards
Cholera 400 212
Diphtheria 1337 56
Polio 266 129
Rabies 65 89
Total of four diseases 2068 486

Firearm injuries   >4,000,000 3

One of the executive orders signed by Obama on Jan. 16 directed the Centers for Disease Control to research the causes and prevention of gun violence, based on a legal analysis that congressional restrictions on spending money to advocate for gun control does not apply to such inquiries.

There is a bit of irony here.
While the 40-percent figure appears overstated and out of date, it remains the most cited statistic on the secondary market because foes of gun control have thwarted extensive research on guns. Advocates of gun controls thus continue to rely on a flawed statistic nearly two decades old.