Paper discussing economic rationale of IQ-based hiring practices
I believe I know which paper you're referring to. My guess is the widely cited Schmidt &amp; Hunter (1998) paper. The paper summarizes 85 years of practical and theoretical implications of research in personnel selection. To see that they address what you're asking for, here is a quote from the paper


  If a superior worker is defined as one whose performance (output) is at the 84th percentile (that is, 1 SD above the mean), then a superior
  worker in a lower level job produces 19% more output than an
  average worker, a superior skilled worker produces 32% more
  output than the average skilled worker, and a superior manager
  or professional produces output 48% above the average for those
  jobs. These differences are large and they indicate that the payoff
  from using valid hiring methods to predict later job performance
  is quite large.


Then later they state


  At one extreme, if an organization must hire all who
  apply for the job, no hiring procedure has any practical value.
  At the other extreme, if the organization has the luxury of hiring
  only the top scoring 1%, the practical value of gains from selection
  per person hired will be extremely large. But few organizations
  can afford to reject 99% of all job applicants.


However, a more recent paper on the subject has been published. That's the Schmidt, Oh &amp; Shaffer (2016), which summarizes 100 years of practical and theoretical implications of research in personnel selection. This paper is an update on the former, so you may as well just look only at this latest one.