In the wake of Friday’s massacre in Paris, a new report says the world is paying the highest price for terrorism since the 2001 attack on New York’s Twin Towers.

In 2014, acts of terror cost the world $52.9 billion — roughly the size of Bulgaria’s entire annual gross domestic product — compared with $51.51 billion in the aftermath of Sept. 11, according to the latest annual Global Terrorism Index by the Institute for Economics and Peace, which has been collecting data since 1997.

To put a price on terrorism, IEP calculates the value of property damage, say from a suicide bombing in a building, and the cost of death and injury, including medical care costs and lost earnings. It doesn’t take into account the increased number of security guards, higher insurance premiums, or city gridlock in the aftermath of an assault.

While the findings do not include the impact of Friday’s carnage in the French capital — those will be quantified in next year’s study — theeconomic consequencesof Europe’s worst terror attack in a decade so soon after January’s Charlie Hebdo shootings will reverberate across the European Union almost immediately.

“There will be impact from this quarter on GDP in France as a result of this because if you can just look at the shutdown of the city for let’s say 48 hours and then there are the ongoing flow-on effects from this as well,” said Steve Killelea, the institute’s executive chairman, by phone from London. “If you beef up the security apparatus, particularly in Europe, as it affects the free flow of people that will have an impact on the ongoing productivity.”

Islamic State — which this year claimed responsibility for attacks on Paris and Beirut as well as the downing of the Russian plane in Egypt — has now overtaken the Taliban in Afghanistan to be the deadliest terrorist group, killing more than 20,000 people last year, the study showed. French President Francois Hollande called IS “the biggest terrorist factory the world has ever known.”

The self-proclaimed caliphate, which spun out of al-Qaeda in Iraq, relies on an increasing number of foreign fighters coming from the developed world. Among non-majority Muslim countries, Russia has the highest number of nationals who have traveled to Syria and Iraq to fight, followed by France.

In the last two decades, high-profile assaults on European capitals from London to Madrid were the work of organized extremist groups. Still, about 70 percent of deaths from terrorism in western countries between 2006-2014 were the product of unaffiliated lone wolves motivated by their anti- government sentiments or opposition to immigration, gay rights, or abortion, according to the report.

Terrorism carries the biggest human and economic toll is in emerging markets, where groups can exploit lawless spaces neglected by failing or weak governments. By region, the Middle East and North Africa were the most affected, accounting for 13,426 of total lives lost to terrorism in 2014.