More than one a day.

That is how often, on average, shootings that left four or more people wounded or dead occurred in the United States this year, according to compilations of episodes derived from news reports.

Including the worst mass shooting of the year, which unfolded horrifically on Wednesday in San Bernardino, Calif., a total of 462 people have died and 1,314 have been wounded in such attacks this year, many of which occurred on streets or in public settings, the databases indicate.

It is impossible to know whether the number of such shootings has risen in recent years because the databases go back only a couple of years. More data is available for mass shootings calculated by a different standard, one used by congressional researchers and other experts who study mass killings: four or more dead. But experts fiercely debate whether mass shootings by that more deadly standard have remained level or ticked up slightly in recent years.

Nonetheless, the stream of shootings this year — including an attack last week on a Planned Parenthood clinic in Colorado that left three dead and a shooting in October at a community college in Oregon that left 10 dead, including the gunman — has intensified the debate over the accessibility of powerful firearms.

Two databases that track mass shootings that leave four or more dead or wounded — shootingtracker.com and gunviolencearchive.org — depend on news accounts and are not official. Nonetheless, they give an indication of the widespread nature of such episodes. Since January, there have been at least 354 such cases in about 220 cities in 47 states, according to shootingtracker.com.

In November, six people were killed, five of them shot to death at a campsite in East Texas; 17 were wounded in a shootout as a crowd watched the filming of a music video in New Orleans; and four died, including twin 5-month-olds, in an episode of domestic violence in Jacksonville, Fla. So far this week, five people were wounded Sunday morning in a shooting in Kankakee, Ill., and a shooting Wednesday, before the San Bernardino attack, left one woman dead and three men wounded in Savannah, Ga.