Boko Haram The World's Deadliest Terror group

(CNN)With its reign of terror in the Middle East, its claim to have brought down a Russian passenger jet and now, the atrocities in Paris, ISIS has commanded global headlines as the world's most dangerous terror group.

But another militant Islamist organization overtook ISIS to become the world's deadliest terrorist group last year, according to a new report.

Boko Haram, the Islamic extremist group based mainly in Nigeria's northern states, was responsible for 6,644 deaths in 2014, an increase of 317% from the previous year, according to the Global Terrorism Index, released Tuesday.

By contrast, ISIS, the terror group to which Boko Haram reportedly pledged allegiance in March of this year, was responsible for 6,073 deaths.

Between them, the two groups were responsible for more than half (51%) the deaths attributed to terrorism, in the deadliest year on record for terror, according to the report.

Internationally, deaths from terrorism experienced a "dramatic rise" in 2014, increasing by 80% from the previous year, according to the study by the Institute for Economics and Peace.

There were 32,658 people killed in terrorist attacks last year -- nine times more victims than there were in 2000, it says.

School kidnappings, market bombings

Boko Haram, whose name means "Western education is forbidden" in the local Hausa dialect, gained international notoriety for its raids on schools, in which hundreds of girls have been kidnapped.

An estimated 276 teenage girls were snatched from a boarding school in Chibok in Nigeria's Borno state in April of last year, sparking the #bringbackourgirls campaign on social media.

The group -- whose elusive leader, Abubakar Shekau, has a $7 million U.S. government bounty on his head -- has also pursued a ruthless campaign of bombing marketplaces throughout Nigeria.

The country was rocked by two such blasts within 24 hours this week, with at least 31 people killed Tuesday in the northeastern city of Yola, according to a local Red Cross official, and 15 killed in Kano, about 400 miles (645 kilometers) to the northwest, according to police.

Full reports: edition.cnn