Why is there a savings surplus in the euro zone?

Since 2012, the euro zone has had significant excess savings over investment; how can this be explained? Possible explanations are: A low level of public investment, due to the effort to reduce fiscal deficits; A low level of housing investment after the 2008-2009 crisis; A low level of corporate investment, either because of sluggish demand or corporate deleveraging; A high level of household savings, particularly in anticipation of ageing; Company earnings that exceed their investment needs; The effort to reduce the fiscal deficit (increase in the tax burden, reduction in public spending other than public investment). The relevant explanations for the euro zone’s savings surplus since 2012 seem to be: The weakness of all forms of investment; Excess corporate savings; A return to structural fiscal surpluses caused by the increase in the tax burden, This suggests that it would have been better to: Increase public investment; Introduce investment tax incentives for companies.