No country is completely free of corruption, but some are cleaner than others.

Last year, corruption was rife in 68% of the world’s countries, including half of the Group of 20 nations, based on Transparency International’s Corruptions Perceptions Index. On the plus side, most countries’ scores improved from the previous year.

The Berlin-based organization’s gauge, which measures widespread corruption in the public sphere, factors in instances of abuses of power, secret dealings, bribery, child labor, human trafficking, environmental destruction and terrorism, among other factors.

Taking a longer perspective, Greece, Senegal and the U.K. showed the biggest improvements since 2012 while Brazil, which is engulfed by the Petrobras corruption scandal, Australia, Libya, Spain and Turkey saw their scores skid sharply.

The countries that landed at the bottom of the list are ones that continue to be rocked by open conflict and disastrous levels of poverty and inequality: Angola, South Sudan, Sudan and Afghanistan. North Korea and Somalia tied for the dubious honor of most corrupt country in the world. Other countries in the bottom 10 are Guinea-Bissau, Libya, Iraq and Venezuela.

Source: Transparency International

A girl sits in front of a tent in a makeshift camp for people displaced in Angola's brutal 27-year civil war which ended one year ago. Getty Images

Angola

Roughly 70% of the people living in Angola lives on $2 a day or less. It’s also considered the deadliest country for children, ranked No. 1 in terms of places where kids are most likely to die before turning 5. Bribery runs rampant, and despite legislation being passed in 2014 forbidding money laundering, the practice continues to prop up business activity.

A South Sudanese soldier. Getty Images

South Sudan

As oil revenue declines, South Sudan’s economy has gotten crushed and corruption has spiked, according to a report by The Sentry, an organization co-founded by actor George Clooney. The report says the oil sector is greatly mismanaged, and the overall financial system is exploited by a small group of elites to gain power and profits. Fighting for control continues to erupt around key oil sites across the country.

Children flock with containers hoping to collect food at a village in Sudan. Getty Images

Sudan

Decades of civil war have left Sudan with limited government and deteriorating infrastructure, opening the door to widespread corruption. Government authorities continue to be linked to corrupt practices such as embezzlement, cronyism and bribery.

The site of a suicide car bombing near the international airport in Kabul in December. Getty Images

Afghanistan

In Afghanistan, millions of dollars intended for the war-torn country’s reconstruction have either been wasted or stolen. Conflict in the country continues to flare up as attacks from the Taliban have escalated this past year, undermining the government’s efforts to rein in systemic corruption.

Read:U.S. burns $43 million to build gas station in Afghanistan

South Korean veterans burn placards of the North Korean flag and its leader, Kim Jong Un, during a protest in August. Getty Images

North Korea

At the bottom of the list: North Korea, a totalitarian state that remains isolated from the rest of the world. Collecting data is nearly impossible in a country where virtually everything is controlled by the state. Dictator Kim Jong Un has even managed to ramp up the country’s combative rhetoric and behavior toward nearby countries and the U.S. since his father’s death in 2011, claiming earlier this year that the country had successfully detonated a hydrogen bomb.

A body lies in the rubble next to damaged cars near the Jazeera Palace hotel following a suicide attack in Mogadishu. Getty Images

Somalia

Somalia turns up at the bottom of the index again, tying North Korea for world’s most corrupt country. Violence and political instability have kept Somalia locked in state of fear and corruption. The country continues to rely on foreign aid, as the government has been unable to provide basic services or a judicial system.

Overall, Sub-Saharan Africa was hit hardest on the list, with 40 of the region’s 46 countries suffering from corruption.