The Failure of Net Investment (as a % of GDP) to Return to its Historic Levels

This began life as a comment on a blog post.  I have decided to post it here...

When I think about investment spending, I tend to focus most on net investment--total investment minus depreciation--as a % of GDP.  Private sector investment is not0riously volatile, falling dramatically during recessions.  So, for example, net investment (as a % of GDP--from here on out, all net investment figures will be as a % of GDP)fell from 7.5% around 1965 to just less than 4% in the 1970 mini-recession, rebounded to 7% by 1973, fell to about 2.2% in the 1974-75 recession, rebounded to 7% by 1980, fell to a little more than 2% in the 1980-82 recession, rebounded to about 6.5% in that recovery, and, from the mid-1980s to about 1992, fell to abuot 1.5%.
During the Clinton years, investment again recovered, to about 6%.  In the recession beginning in 2000, it fell to about 2%.  The recovery was fairly weak--to only about 3.5% by 2007.

Then--the real collapse.  Net investment turned negative for the first time since the late 1940s-- minus 2%.  The recovery was again weak, to just over 4% by 2009.  Since 2009, net investment has not exceeded 3.5% of GDP in any calendar quarter, and is now about 2.5%, which was the bottom-of-a-recession level in the 1960s and 1970s.  
This remarkably low level of investment comes despite the tax cuts, despite everything.  Right now, and, really, since the 2000 recession, the best done in terms of net investment is , essentially, no better than the worst from 1960 to about 2005.