Hmmm, that's an interesting question.  I don't have anything in my library like that.  

When I have to compile obscure labor statistics,  I contact Jay Meisenheimer, with the Dept. of Labor, Labor Statistics.  He's always been very helpful.  His number is 202-606-6378.  

This census may also have some information about this. 

Good luck!!

Rosada Bennett, Librarian

Federal Mine Safety and Health Review Commission
1730 K St., NW  6th Floor
Washington, DC  20006
(202) 653-5459
(202) 653-5030 - fax