Among single people, 78% list themselves as single, 14% don't list a status, and the other 8% lie by saying they're in a relationship.

People who are dating but not engaged are the only ones who reported using the "it's complicated" choice.  6% have their relationship status as "it's complicated."

3% of people who are engaged list themselves as single.  So do 1% of married people.

For people who say they're in a relationship but don't list the person's name, the main reasons are privacy and crazy exes.

55% of the people surveyed plan on going on a date tonight, or having a night in with their significant other.  6% are planning on having a first date.  22% will spend time with their friends and 12% are not planning on celebrating at all.  (The remaining 5% responded with "other".)

(Mashable)

Here's a handy table of the Facebook "relationship" icons: