Australia takes a national census this week, and it is expected that one-in-three households will choose the online option to fill out the 60-question form. The nation last took a census in 2006, and the 2011 count marks a century of census-taking for Australia.

Unlike the U.S. Census Bureau, which does not ask about religion, the Australian Census does include a religion question. Although filling out the census form is required, answering the religion question is optional. A 2010 essay commissioned by the Pew Forum on Religion and Public Life explains the history of the U.S. Census Bureau’s questions about religion, which stopped several decades ago.

On the topic of same-sex relationships, although the Australian government does not recognize same-sex marriage, same-sex couples who married in other nations will be included in the “married” category for the first time when data are reported next year. The U.S. Census Bureau has promised to release counts from the 2010 Census of same-sex couples who describe themselves as married, which is a break from past practice.

As in the U.S. Census, the Australian census has made changes in the way it tabulates race and ethnic origin. It was not until 1971 that Aboriginal and Torres Strait Islander populations were included in the official count.

The Australian Bureau of Statistics promises that the personal detail on census forms will remain confidential for 99 years; as of Aug. 8, 2110, personal information will be made available to professional researchers as well as people interested in their family histories. The U.S. Census Bureau keeps personal information confidential for 72 years; 1940 Census data are to be released in 2012.

The Australian statistics agency offers people the option not to have their information released. In 2006, according to the agency, more than 56% of Australians opted to release their information in the future.