( CNN) Press freedom in the United States and across the world is at its lowest phase in 13 years, according to a new report by the independent watchdog group Freedom House.

The group attains its annual analysis based on the legal, political, and economic environment for the reporters in the previous year. The countries are rated on a scale of 0-100, and the closer to zero a country is, the freer its press.

This year's report changed the United States' press freedom rating by two points, from 21 to 23 — its worst rating in more than a decade. The group attributes this to a worsening political environment, the rise and polarization of partisan media outlets and an increase in Russian-sponsored propaganda related to the 2016 general elections.