[The fight to retake the last vestige of the Islamic State’s caliphate in Iraq and Syria has begun.]

The Islamic State carried out 14 successful attacks in Europe and North America in 2015, 22 in 2016 and 27 in 2017, according to data collected by George Washington University’s Program on Extremism. But in the first eight months of this year, it only carried out four.

“It’s an absolutely dramatic dip,” said the program’s director, Lorenzo Vidino.

The scale of attacks has also fallen. The largest toll in a single attack fell from 130 in 2015, to 86 in 2016, to 22 at the pop concert in Manchester in 2017. So far in 2018, the worst single-day toll was in the aisles of a supermarket in Trèbes, France, where a man acting in the name of the Islamic State gunned down three people in March.

The Islamic State, also known as ISIS, has lost 99 percent of the land it once held in Iraq and Syria, and the fight to evict it from the last vestige started this week. Some analysts have linked the drop in activity to the loss of territory.

But the number of attempted attacks in Europe has remained unchanged, according to data collected by the Center for the Analysis of Terrorism in Paris. That data suggests that while the Islamic State’s capacity may have been diminished, its effort has not.