The death rate among the California mission Indians during the mission era (1769-1834) was about 90%.
And, there is increasing evidence that introduced diseases had already significantly lowered populations by the time Spanish colonization began.
Source? That's an absurd statistic if I've ever seen one.
The Aztec calendar had it right ~ End of the World.
The English undertook a propaganda campaign against the Spanish regarding New World settlement. It was fairly successful but it wasn't correct.
BTW, the GERM THEORY OF DISEASE didn't get pegged to the wall until the 1800s.