The election of Helle Thorning-Schmidt as the prime minister of Denmark reduces by one the number of countries which have never had a woman as head of state.

Although many of the world’s democratic states have had females as presidents and/or prime ministers – surprisingly, many have not, including the most powerful democracy on Earth, the United States.

Hillary Clinton likely had the best chance to become the first woman president of the U.S. in 2008 until Barack Obama usurped her for the Democratic Party nomination.

In 2012, it seems unlikely that Michelle Bachmann will win the White House, much less gain the Republican nomination.

Other Western countries that have never been led by a woman include Spain, Italy, Greece, Netherlands, Belgium, Sweden and Austria. The most prominent democracy in Asia, Japan, has also always been led by men. Russia and China have also had an exclusively male leadership at the top.

On the flipside, nations that have been ruled by women (elected or otherwise) comprise a bewildering hodge-podge of states: along with the western democratic countries, such diverse states as India, Brazil, Israel, Bangladesh, Liberia, Madagascar, Pakistan, Philippines, Sri Lanka, Mongolia, Mali and Peru have had either female heads of state or female heads of government (or both).

Of course, throughout history, some female chief executives gained power following the deaths of their husbands – the most prominent of this group might have been Isabel Martínez de Perón, who ruled Argentina for less than two years in the mid-1970s following the death of her husband Juan. (She is not to be confused with the more famous Eva Peron).

One of the longest running female elected heads of state was Vigdís Finnbogadóttir, who served as the president of Iceland for sixteen years from 1980 to 1996.

Mary McAleese was the president of the Irish Republic for 13 years from 1997 to 2010; while Tarja Halonen led Finland for 11 eleven years starting in 2000.