It's almost impossible to garner any 'facts' from this either way, no matter which way you swing.
For example (note I do not want to talk about this) , if you look at migration stats, who has given them, how was it worked out and where are they from (as in what organisation gave these details) ?
There is typically an agenda behind even the most simple sodding thing like the above (usually just simply follow the money) and hugely differing numbers etc.
There is ALWAYS some form of bias selection when it comes to this stuff that we are all guilty of, simply as it strengthens our view, you can't change that.