Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: Over 99 percent of all species that ever lived on Earth have gone extinct. Five mass extinctions are recorded in the fossil record. They were caused by major geologic and climatic events. Evidence shows that a sixth mass extinction is occurring now. Unlike previous mass extinctions, the sixth extinction is due to human actions. Answer: 99%
What percentage of all species that ever lived on earth have gone extinct?