What Percent of animals have gone extinct over the history earths existence?

It's not possible to provide an exact percentage, but scientists estimate that the vast majority of species that have ever existed on Earth are now extinct. Some estimates suggest that as many as 99.9% of all species that have ever lived are now extinct. The fossil record indicates that there have been five major mass extinctions in Earth's history, and each of these events resulted in the extinction of a large number of species. The most recent of these mass extinctions occurred about 66 million years ago and wiped out the dinosaurs, among many other species.