The National Association of Insurance Commissioners (NAIC) has ranked the top 25 property & casualty insurance companies and groups by countrywide premium for 2017. Each year, the NAIC releases this report providing market share information that indicates the degree of market concentration in lines of business and identifies leading insurance writers.

According to this year's report, direct premiums written among the top 25 P&C providers totaled over $638 billion in 2017, up from $610 billion in 2016.  Many of the names on the 2017 list are the same as previous years, with a few changes in ranking.

Related: Top 15 writers of 'other liability' insurance for 2017, as ranked by NAIC

Again this year, State Farm took the number one spot with $64.9 billion in direct premiums written, representing a market share of 10.16%. Additionally, the top seven rankings remained unchanged from the 2016 list.

The annual NAIC report is based on filings received by March 19, 2018, when an estimated 97.25% of property & casualty filings were received. More information on the report can be found on NAIC's Research & Actuarial Department website.

The P&C report contains cumulative market share data for the following lines of business: personal auto, commercial auto, workers' compensation, medical professional liability, homeowners and other liability (excluding auto liability) insurance.

Click through the slideshow above to check out the top 15 P&C groups across all lines in 2017.

Related: Top 10 total commercial auto carriers, as ranked by the NAIC