The site is should we say opaque, however, there is so much information on it that it has to be worthwhile persevering. When it was first introduced I placed a very adverse comment about it being more productive for me to spend 5 hours on a train in each direction, plus three hours in the archive than to try to use the site. However, after downloading the PDF help document and re-installing Internet Explorer I found it was possible to do meaningful research on it.