Do the math. There are 1.6 billion Muslims. Half are male and 1/3 of males are fighting age (14-40).
From these 266 million fighting age Muslim males, only a small percentage have actually chosen to fight for world domination as required by fundamental Islam.
If 10 percent choose to fight there are 26.6 million Islamic jihadists. If 5 percent, there are 13.3 million Islamic jihadists.
If only one percent of fighting age Muslim males choose to fight, there are 2.6 million (2,600,000) Islamic jihadists fighting for world domination in the Cause of Allah.