Answers: Look here for a summary...
cancer.gov/newscenter/pressreleases/WINSBreastStudy" rel="nofollow">http://www.cancer.gov/newscenter/pressre...
Here is a fairly recent article published beside a graph (see Figure 2)
http://jnci.oxfordjournals.org/cgi/conte...
check journal articles from solid journals. You can return with access to them via your uni or a place like The British Library or purely do a google serach.