Some figures on prestige bias in academia

I've put together some numbers on pedigree bias from various websites and sources, and it seems the problem is pervasive in academia: 

• In computer science, business and history, 25% of doctoral granting institutions provide 71-86% of all tenure track jobs (Clauset et al.)
• In computer science, business and history, only 9-14% of candidates get placed at places that are higher-ranked than their institutions
• In philosophy, 88% of initially reported tenure track hires in 2013-2014 were from Leiter-ranked programs 
  
• In philosophy, 37% of initially reported tenure track hires in 2013-2014 had their PhDs from the top-5 schools  
• [UPDATE: Based on Carolyn Dicey Jenning's more complete dataset, this turns out to be a skewed number. She finds 31% of tenure track hires come from top 10-departments
• In English, the top-6 programs get 60% of their hires from other top-6 programs, and 90% are from the top-28 - nobody from the 65+ ranked programs ever gets hired in a top-6 faculty.
• Older data in sociology suggest that the prestige of PhD granting department is one of the main factors in hiring decisions (the other is the selectivity of the undergraduate institution. The authors conclude (rather dryly) "job placement in sociology values academic origins over performance."