Afghanistan has returned to a prominent watchdog group's annual list of countries with the worst records of prosecuting the killers of journalists.

Impunity is "entrenched" in Afghanistan and 13 other countries where journalists are "murdered regularly and their killers go free," the Committee to Protect Journalists (CPJ) said in its 2018 Global Impunity Index report released on October 29.

Pakistan, Russia, Somalia, Iraq, the Philippines, Mexico, and India have been on the list every year since the New York-based media-freedom advocacy group began to compile its index in 2008.

"In the past decade, at least 324 journalists have been silenced through murder worldwide and in 85 percent of these cases no perpetrators have been convicted," the report says.

More than three-quarters of these cases occurred in the 14 countries that CPJ included on this year's index.

"The fact that impunity continues to thrive in many of these countries year after year is a disturbing sign of how deeply rooted the problem is," said Elisabeth Witchel, the report's author. "Impunity is an effective way to silence journalists and creates a void of information."

"Governments must treat these cases as a priority and provide appropriate mechanisms to achieve justice for these journalists and their families," Witchel added.

To establish its annual Global Impunity Index, CPJ calculates the number of "unsolved journalist murders" as a percentage of each country's population.

For the 2018 index, the organization examined journalist killings that occurred between September 2008 and August 2018 and remained unsolved.

Countries with five or more unsolved cases for the period are included.

Somalia tops the list for the fourth year in a row, followed by Syria, Iraq, South Sudan, and the Philippines.

CPJ said there were 18 unsolved killings of journalists in Syria, where Russia and Iran support President Bashar al-Assad's government in a war that has killed hundreds of thousands of people and driven millions from their homes.

Afghanistan was included in the list, ranking fifth, after a suicide bombing killed nine journalists in Kabul on April, in what became the deadliest single day for reporters in the country since the U.S. invasion that followed the September 11, 2001, attacks.

There were 18 unsolved cases concerning the killings of journalists in Pakistan and 17 in Russia. The two countries rank 9th and 11th, respectively.

The others included on the list of 14 countries are Colombia, Brazil, Bangladesh, and Nigeria.