Sandy Hook was horrible, but what about 2013’s overlooked mass shootings?

The 48-page report from Connecticut’s state attorney on last year’s Sandy Hook Elementary School massacre has been released, and it’s full of horrifying details.

Among other things, writes The Times’ Tina Susman, the 20-year-old shooter “kept a spreadsheet of mass murders, hated to be touched and did not allow anyone — including his mother — into his bedroom. He covered his bedroom windows with black trash bags, disliked birthdays and holidays, would not let his mother put up a Christmas tree and made her get rid of a cat because he didn’t want it in the house.”

A sickening reminder of the carnage a year ago. And it made me think: What has happened in the year since? How many other mass killings did we endure?

Sadly, since Sandy Hook — which took 20 children’s lives as well as those of six school employees and the shooter’s mother in December 2012 — we were all again shaken by the senseless killings at Santa Monica College in June (six dead) and the shootout at the Washington Navy Yard in September (13 dead).

We grimaced, groaned; we assimilated those incidents. But there were many more that apparently didn’t even register.

Try this little quiz right now (I did). Ask yourself, your spouse, your son, a friend:

Do you recall the six people slain in Hialeah, Fla., in July by a man who targeted his neighbors?

Or the five children and adults killed in Manchester, Ill., in April by the nephew of a local mayor?

Take one measure of “mass shooting” — one shooter, one time, at least five dead — and yet that’s not enough to sear an incident on our consciousness?

Those outrages created barely a ripple on the national news front. Even at a major newspaper such as this one, photos for many of these tragedies are hard to come by.

And the staccato sound doesn’t stop.

Among the senseless shootings that got me started on this path of our national indifference:

Do we remember the Mohawk Valley shootings in March? When a 64-year-old man in New York shot six people in neighboring towns, killing two in a barbershop and two at a car care business, before being killed by officers in a shootout after a nearly 19-hour standoff?

What about the 25-year-old man in Fernley, Nev., who was arrested in May, days after allegedly killing an elderly couple in their home, then a newspaper delivery man and another couple nearby?

Maybe Joel Silberman said it best on the Opinion L.A. blog: “Who cares?”

As he wrote just a few weeks ago, after yet another senseless shooting — this time at LAX:

“In fairness, even horrifying attacks are relative: One adult dead and many wounded is not equivalent to the mass slaughter of schoolchildren that we witnessed 10 1/2 months ago. That was worse. And reporters for local news outlets — including The Times — have more than proven that they, at least, are not numb, with their extensive coverage of the LAX story.

“But the question remains: Who cares? Literally, who? When people care, the atmosphere is like it was after the Boston Marathon bombings or the Newtown, Conn., shooting. Can anyone honestly claim that we are in that kind of atmosphere right now? If a body falls — or five of them fall — in a forest of exhausted indifference, do they make a sound?”

Is Silberman right?

“Ultimately, the increasing frequency of mass shootings has given us a choice: live in panic and despair, or learn to suck it up and deal. Given the options of jitters or jadedness, the impulse to keep calm and carry on is understandable.”

Yup, that makes sense.

But what if we were those families in Fernley? Or Mohawk Valley? Or Hialeah?

Would we remember then?

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Sara Lessley is a freelance journalist and editing coach in Los Angeles.