The 1.8 billion is from 2015.Because struggling against Russia isn't enough, another front must be opened against 1.8 billion Muslims.
I think Turkey will be the biggest loser for Europe decline and this clash of European values with Muslims.
While the world’s population is projected to grow 32% in the coming decades, the number of Muslims is expected to increase by 70% – from 1.8 billion in 2015 to nearly 3 billion in 2060. In 2015, Muslims made up 24.1% of the global population. Forty-five years later, they are expected to make up more than three-in-ten of the world’s people (31.1%).