You probably didn’t know it, but this is “National Singles Week,” an observance that — according to the Census Bureau — was started by the Buckeye Singles Council in Ohio in the 1980s to celebrate single life and recognize singles and their contributions to society.

“The week is now widely observed during the third full week of September as ‘Unmarried and Single Americans Week,'” the Census Bureau said, an acknowledgment that many unmarried Americans don’t identify with the word “single” because they are parents, have partners or are widowed or divorced.

So, in observance, a few demographic facts from the Census treasure trove:

96.6 million: Number of unmarried Americans 18 and older in 2009 , or 43% of all U.S. residents 18 and older.

88: Number of unmarried men 18 and older for every 100 unmarried women in the United States.

61%: Percentage of unmarried Americans 18 and older who had never been married.

24%: Percentage of currently unmarried Americans 18 and old who had been divorced.

15%: Percentage of currently single Americans 18 and old who were widowed.

16.2 million: Number of unmarried Americans 65 and older, 17% of all those unmarried and single over age 18.

45%: Fraction of all households maintained by unmarried men or women, 52.5 million in all.

31.7 million: Number of people who lived alone, 27% of all households, up from 17 percent in 1970.

For more: “America’s Families and Living Arrangements: 2009”