Job Loss, Job Finding, and Unemployment in the U.S. Economy Over the Past Fifty Years
The author estimates of separation rates and job-finding rates for the past 50 years, using historical data informed by detailed recent data. The separation rate is nearly constant while the job-finding rate shows high volatility at business-cycle and lower frequencies.
Link
http://www.nber.org/books/macro20/hall7-26-05.pdf