Sasha Madin writes to us with a video he has made charting the changes in population among major religious affiliations in the world for the last 75 years.  I haven't been able to verify the underlying statistical data, but it looks consistent with my understanding of religious populations.

He writes:

There's some mind-blowing numbers (especially past 1990s trend) when you put it all together in a visual way.

I'd say that's quite true.  I don't think it is much of a spoiler to say a focus on Islam is the key here.

This takes under three minutes.  It's worth a look: