Traffic on I-80 in central Iowa.

At least two more people died in traffic crashes in Iowa Tuesday, increasing the total for the year to more than 100.

Dennis Kleen tracks crash data for the Iowa Department of Transportation. “Compared to the previous five years, we had three years where we weren’t at 100 yet, so we’re higher than we have been over those other years,” Kleen said.

There were 320 people killed in traffic crashes in Iowa in 2015. Last year, that number rose to just over 400. While there are likely several contributing factors, Kleen notes there’s been an increase in vehicles on Iowa’s roads.

“Vehicle miles traveled was higher than it had been in previous years, gas prices were a little bit lower and a little more stable, so there’s more traffic out there,” Kleen says. Another factor in the rise in traffic fatalities is unbelted drivers. Kleen says over 40 percent of the people killed this year in Iowa traffic crashes were not wearing a seat belt.

“We’ve got a 93 or 94 percent (seat belt) compliance rate in the general public, so a lot of people who die in crashes aren’t belted,” Kleen says.

The relatively warm weather over the first four-and-a-half months of this year has also contributed to a rise in motorcycle fatalities. “We’re at 12 so far this year and last year, through April, we were only at three,” Kleen said. At this time last year in Iowa, the traffic fatality count was 120 — 20 more than this year.