Ok, there are approximately 78 million people under 18 in the US.
44% of ~208k is ~91,520.
That means the amount of people under 18 who have had sexual assaults against them reported in one year is around 0.12%
And that isn't counting multiple offenses on the same victim.
So, the annual rate of reported sex assaults on minors is a little more than one-tenth of one percent.
There are approximately 160 million females in the US, total. A simple majority would be just over 80 million. A great majority isn't really quanitifiable, but is somewhere higher than that.
So, I think the statement in the original post is probably far from accurate, fortunately.