Across the country, 350,000 observations have been made.

According to the national average, 96 percent of motorists have a seat belt.

In Sörmland, where 9,000 observations have been made, the proportion is 94 percent.

Most of the observations are made on smaller streets in urban areas, where belt use is lowest.

According to Lars Nordquist at NTF in Sörmland, one reason why Sörmland is below the national average may be the county's relatively low socio-economic index, which may mean that fewer people can afford to buy newer cars with seat belt warnings.

The proportion who have a belt is increasing in the county, according to NTF.

But there are still challenges.

- Above all, we see that belt use is significantly lower in terms of accidents with serious injuries or fatalities, says Nordquist.

According to NTF, every third passenger car driver killed is unbelted.