What percentage of the earths surface has been affected by human activities?

Some parts of the Earth's surface have been affected more profoundly by human activities than other parts, but all parts have been affected to some degree, so my answer is 100%. Don't forget, global warming affects the entire globe (to give just one example of how humans have affected the Earth). Various forms of air pollution and water pollution have penetrated to the most remote parts of the world. Nothing is entirely unaffected.