This figure is still being used even though it is over 30 years old and relates to Canadian women. It may indeed be true, in fact it could be more, but no such research was carried on male victims so there is no reciprocal data. Its use without the reciprocal data again means the male voice and statistics on male victims are not being used.
So where does it come from?
The source is Canadian academic Dr. Peter G Jaffe and the research paper is called An integrated response to wife assault : a community model.
Some sources say 1982 and others say 1984, but the research took place in 1981. And it was only conducted with female victims. Male victims were certainly never recognised way back then.
At least we know in the UK now, figures for female victims have reciprocal figures for male victims, even if some selectively only choose to use the female victims still.