Atheism, agnosticism, deism, skepticism, freethought, secular humanism or general secularism is increasing in Australia. Post-war Australia has become a highly secularised country with the proportion of people identifying themselves as Christian declining from 96% in 1901 to 64% in 2006 and those who did not state their religion or declared no religion rising from 2% to over 30% over the same period. The 2006 census indicated 18.7% or 3,706,555 people self-described as having "no religion" - a rise of three percentage points since the 2001 census. It saw the largest increase in numbers of 800,557 people. Answering the Census question on religious affiliation was optional and a further 2.4 million (11.9%) did not state their religion (or inadequately described it). Thus approximately 30% of Australians did not state a religious affiliation in the 2006 census. According to Norris and Inglehart (2004), 25% of those in Australia do not believe in God.