A study of bicycling fatalities from 1975-2012 illustrates some non-surprising trends.
Kid (under 15) fatalities decreased 92 percent! Fatalities among cyclists aged 35-54 nearly tripled, and 87 percent of those fatalities were men. Fatality rates for women remained steady.
The decline in child fatalities might be "attributable to fewer child bicycle trips." Do you s'pose? When I was a kid (too early to be included in this study), there were probably 150 bikes parked out front of Roosevelt Elementary. Nowadays there are maybe a dozen bikes out front of Monroe Elementary, where my kids attended and my granddaughter now attends. (She can't ride her bike - her grandma is absolutely certain she'd be either run over or abducted somewhere along the 3/4 mile ride.)
How about those grownup guys that are getting kilt? Well... the study says from 2000-2012 "the number of U.S. workers who traveled to work on a bike increased 61 percent," and mostly among men 25-64.
Fatalities varied from state to state, with Florida having the most (I assume by percentage), and Vermont the least.
Overall, the fatality rate dropped from 955 in '75 to 717 in '12.
What else has changed in the past 40 years? As a casual observer, I'd say a primary change is... there were zero cellphone/"smart"phone users in '75, and nowadays pretty much everybody has one, and many are yammerin' or pokin' as they drive along. And obviously if they kill a few bike riders, society considers that acceptable "collateral damage."
The study suggests better bike infrastructure, enforcement, helmet use, and better education on safe bike/motorist behaviors as keys to reduce fatality rates. I agree, particularly on the enforcement and education.