I thought this news article from a Louisville outlet offered some interesting data on the emerging teacher shortage. The piece includes many links to national data sources and some comments on what teacher preparations local to the area are doing to address the trend.
Among other statistical indicators, I found the data on the changes in just the last five years to be discouraging. The discussion of reported causes did not reveal much I found new. I accept the impact of those factors listed, but the list includes the same factors that have been evident for some time and nothing included would seem to explain the recent changes.