(CBS NEWS) – The number of mass shootings across the U.S. so far in 2019 has outpaced the number of days this year, according to a gun violence research group. This puts 2019 on pace to be the first year since 2016 with an average of more than one mass shooting a day.

As of Sunday, which was the 216th day of the year, there have been 251 mass shootings in the U.S., according to data from the nonprofit Gun Violence Archive, which tracks every mass shooting in the country. The Gun Violence Archive defines a mass shooting as any incident in which at least four people were shot, excluding the shooter.

The toll of 251 mass shootings include five high-profile rampages in the past eight days, in which more than 100 people were shot:

*A shooting in a historic district of Dayton, Ohio, with 9 people killed and 27 injured.

*A shooting at Walmart in El Paso, Texas, with 20 people killed and 26 wounded. It was the deadliest shooting of the year.

*A shooting at the Gilroy Garlic Festival in the San Francisco Bay Area, with three people killed and 15 injured.

*A shooting at a Brooklyn block party, with one person killed and 11 injured.

*A shooting at a Walmart in Southaven, Mississippi, with two people killed and two injured.

Before the El Paso attack, the deadliest mass shooting of 2019 happened in a municipal building in Virginia Beach, where a former city employee killed 12 people and injured four.

The Gun Violence Archive says there have been 33,028 total shooting incidents in 2019 as of Sunday, resulting in 8,734 deaths and 17,308 injuries.

The last time the mass shooting toll topped days of the year was 2016, which had 382 mass shootings — the most in any year since the Gun Violence Archive started keeping track. The past two years came close, with 346 mass shootings in 2017 and 340 in 2018.

© 2019 CBS Interactive Inc. All Rights Reserved.