Okay so the 40% was used more back in the day,
in 2005 a study showed it was 3%....
Main article: False accusation of rape
FBI reports consistently put the number of "unfounded" rape accusations around 8%.
However, "unfounded" is not synonymous with "false" allegation.
The largest study, published in 2005, was based on 2,643 sexual assault cases and found 3% of false reports.
A much criticized
1994 study of 109 rape complaints made between 1978 and 1987 found 41% of false allegations.
A 2006 review of studies of false reporting in the United States, New Zealand and the United Kingdom concluded:
"Two conclusions can be drawn from this review of literature on the prevalence of false rape allegations. First, many of the studies of false allegations have adopted unreliable or untested research methodologies and, so we cannot discern with any degree of certainty the actual rate of false allegations. A key component in judging the reliability of research in this area relates to the criteria used to judge an allegation to be false. Some studies use entirely unreliable criteria, while others provide only limited information on how rates are measured. The second conclusion that can be drawn from the research is that the police continue to misapply the no- crime or unfounding criteria and in so doing it would appear that some officers have fixed views and expectations about how genuine rape victims should react to their victimisation. The qualitative research also suggests that some officers continue to exhibit an unjustified scepticism of rape complainants, while others interpret such things as lack of evidence or complaint withdrawal as proof of a false allegation. Such findings suggest that there are inadequacies in police awareness of the dynamics and impact of sexual victimisation and this further reinforces the importance of training and education. However, the exact extent to which police officers incorrectly label allegations as false is difficult to discern."