The terror group ISIS along with its predecessors and affiliates carried out over 4,900 attacks between 2002 and 2015, killing more than 33,000 people in assaults that stretched from the Middle East to western nations, according to a new study.

ISIS-related attacks comprised 13 percent of all terror attacks globally during the 13-year period, according to research released Tuesday from the National Consortium for the Study of Terrorism and Responses to Terrorism at the University of Maryland. In addition to killing tens of thousands of people worldwide, assaults by ISIS, also known as the Islamic State or ISIL, have caused 41,000 injuries and involved 11,000 hostage takings or kidnappings. ISIS and its affiliates caused one quarter of the deaths from terror attacks during the period.

While ISIS did not assume its current name until 2013, researchers evaluated the patterns of ISIS-related attacks beginning in 2002 by looking at assaults perpetrated by its predecessors. The study, which was funded by the Department of Homeland Security, also examined attacks carried out by ISIS militants in its so-called "caliphate" in Iraq and Syria, attacks by affiliated organizations such as the Khorasan Province in Afghanistan and Pakistan, and ISIS-inspired attacks.

President Obama has sought to highlight the progress of the U.S. military campaign against ISIS in the Middle East, as Iraqi forces have seized key territories from the terror group in recent months. These forces, backed by U.S. airstrikes and ground support, are gearing up to retake Mosul, the terror group’s de facto capital in Iraq. The White House is now also looking to cooperate with Russia to combat ISIS in Syria, where the civil war between Bashar al-Assad and opposition groups has complicated efforts against the terror group.

The new research underlines how ISIS has inspired attacks abroad and expanded the lethality, frequency, and geographical scope of assaults since its emergence. The group began as a small terror network lead by Abu Musab al-Zarqawi, a militant Islamist from Jordan, and claimed its first kill in the death of American diplomat Laurence Foley in October 2002.

"Since then, the group … has undergone a complex evolution, including name changes, leadership changes, and shifts in allegiance to other Salafi-jihadist organizations, most notably al-Qaida," the researchers wrote. "In addition, the reach of ISIL’s violence surpasses its own membership, to include attacks carried out by other groups and individuals who have pledged allegiance to ISIL regardless of whether or not formal ties exist."

ISIS and its allies ramped up attacks between 2013 and 2015, after leader Abu Bakr al Baghdadi announced that the group would expand to Syria. Attacks increased twofold in 2014 over the previous year, with militants averaging 106 attacks per month. The same year, Obama referred to ISIS and other al Qaeda-linked groups in the Middle East as a "jayvee team" in an interview with the New Yorker. Months later, ISIS executed American journalist James Foley in a video recording dispersed over the internet.

The rate of ISIS-related attacks last year was consistent with data from 2014, the terror group and its affiliates carrying out roughly 102 attacks each month, according to researchers.

Between 2013 and 2015, attacks were largely concentrated in Iraq and Syria but also branched out to other nations including Turkey, Libya, Israel, and France. While the majority of attacks were perpetrated by the group’s core militants in Iraq and Syria, ISIS also inspired attacks in western nations including the United States. The terror group inspired 26 assaults in 2014 and 2015 that killed at least 50 people, including the perpetrators, eight of which occurred in the United States.

The first such attack in the United States took place in April 2014, when a Seattle man shot someone dead in retaliation for the U.S. military involvement in Iraq and Afghanistan. Ali Muhammad Brown, who killed three other people, was later found to have been on the federal terror watch list and to have pledged to follow ISIS in a journal entry.

The newly released study does not include attacks that occurred this year, meaning it does not cover the June gun attack in Orlando perpetrated by an ISIS sympathizer that killed 49 Americans in the worst domestic terror attack since September 11, 2001.

Experts told the Washington Free Beacon last month that ISIS will continue to instigate large-scale attacks in the Middle East and western countries even as it weathers territorial losses in Iraq and Syria. The group has leveraged social media to reach sympathizers and pro-ISIS hacking groups have disseminated "kill lists" online targeting U.S. civilians and military, government, and law enforcement personnel.

The State Department assessed ISIS as the greatest global terror threat in 2015 in a June report despite territorial losses, highlighting the group’s ability to leverage technology and encourage external attacks.