Agnosticism is the belief that the existence of God or other spiritual beings is unknown or unknowable. English biologist TH Huxley coined the term in the late 19th century but the earliest documented agnostic ideas are from ancient India and ancient Greece (5th-century BCE). Types of agnosticism include those who actively deny the knowability of the existence of a deity, those who remain open to the possibility of evidence to prove one way or the other, and those who claim not to know or care whether any deity exists. Hinduism has a strong tradition of agnostic ideas. Many atheists deny that agnosticism is separate from atheism. The percentage of people in the US and Britain who identify as non-religious has climbed rapidly in recent years. In Britain data suggests the figure is now more than half the population. It has been estimated that about 7% of people worldwide are non-religious.