considering the total 'x' number of recruitment happening in a year, what is the percentage contribution of recruitment happening through linkedin? second question is out of total 'y' applicants applying to the posted jobs on linkedin, what is the success rate? these questions arise because the companies get applicants via a great variety of means (job sites, consultants, their own website ..etc) then they can easily check the profile of candidates on linkedin, if one can get some idea on the above two questions, we can co-relate or understand the necessity as why companies post jobs on linkedin!!
I am not sure of the specifics you're asking, it seems like a lot of technical data. This might help in your search for these statistics though: