This entry isn't about a single prophecy, but rather a series of individual prophecies covering judgments, war, famine, plagues and other events that will happen both during the Tribulation period, starting from approximately around the time of the Rapture forward to the second coming in which a massive amount of death and world depopulation occurs.  At the start of this period the world population will potentially be as high as 7.5 billion.  By the time of the second coming, when this will all end, there will be less than 500 million people left on Earth, possibly as few as one million, a reduction of up to 99% of the Earth's population that existed at the time of the rapture.  But at the absolute most, no more than 10% of those alive at the time of the rapture will still remain at the end.