Fewer than 400 women have reported rapes in each of the last four years, Kristeligt Dagblad newspaper reports.
For years, the annual number used to be considerably higher at around 500 reported rapes.
According to public health specialist Karin Helweg-Larsen, the decline shows that young people are getting better at respecting each other's limits.
"There's more sex in the public space than ever before – like in reality shows where the participants have sex on live TV – but the development has also created a debate on personal limits," Helweg-Larsen told Kristeligt Dagblad.
That could have led to the decline of date rapes in which the victim and assailant already know each other. Those cases amount to 60 percent of all rape cases nationwide.
"A sexualisation of the public sphere may have made young people take a stand and decide what they want to be a part of," Helweg-Larsen said.
Not all cases are reported
At the help centre for rape victims in Odense, the decline in reported rapes is met with scepticism.
Lone Hedemand, the head of the help centre, says many women never report rape.
"It doesn't necessarily prove that there are fewer rapes," Hedemand told DR Nyheder. "There have been stories about fake reports lately, so the women may hesitate when they want to report a rape."
The Justice Ministry estimated in 2010 the actual number of annual rape victims to be around 3,000, but a majority of the victims never report the incident to the police, according to Kristeligt Dagblad.
"Many women avoid reporting rapes because the first emotion they feel after they have been sexually abused is guilt," Hedemand said.