There have been more mass shootings in the US than days in 2015.

A Reddit-based Mass Shooting Tracker keeps count of incidents in which at least four people are killed or injured by gunshots, based on media reports.

Including the shooting in San Bernardino, California, on Wednesday, there have been a total of 352 mass shootings in the US this year, according to the Mass Shooting Tracker. In the 336 days that have passed so far in 2015, there was at least one mass shooting on 208 of those days: 62% of days in 2015 had at least one mass shooting. On 81 days, there were at least two separate mass-shooting incidents.

The Washington Post produced a devastating calendar using the tracker's counts, showing the enormous number of shootings that have taken place this year.

This chart shows the cumulative count in the US over the course of 2015:

Business Insider/Andy Kiersz, data from Mass Shooting Tracker

Wednesday's shooting in California has left at least 14 dead and at least 14 more injured, police said. The incident came just five days after another high-profile shooting — at a Planned Parenthood clinic in Colorado Springs, Colorado, which left three people dead and injured nine more.

US President Barack Obama has sounded increasingly exasperated in the wake of recent mass shootings, saying after last week's incident at a Colorado Planned Parenthood that the US is "not normal" when it comes to gun violence.

"This is not normal. We can't let it become normal. If we truly care about this — if we're going to offer up our thoughts and prayers again, for God knows how many times, with a truly clean conscience — then we have to do something about the easy accessibility of weapons of war on our streets to people who have no business wielding them. Period. Enough is enough," he said.

There were 32 mass shootings in November, according to the tracker. Wednesday's shooting in California constituted the first mass shooting of this month.