Shocking figures: US academics find 'dramatic' growth of swearing in books | Books | The Guardian

Overall, they found that writers were "significantly more likely to use each of the seven swearwords in the years since 1950", with books published in 2005-2008 28 times more likely to include swearwords than books published in the early 1950s.

"I had guessed that the use of swearwords would increase, but I was surprised that the increase was so large - 28 times more," Twenge said.

The paper, which has just been published in the journal Sage OPEN, says: "American culture increasingly values individual self-expression and weaker social taboos, and these trends are manifested in the increasing use of swearwords."