On an unweighted average basis, European shadow economies are 22.1% of total economic activity or around $3.55 trillion (as large as Germany's whole economy). A report by Tax Research, suggests that Austria and Luxemburg have the smallest shadow economies in the euro area at 9.7% of GDP, while Bulgaria at 35.3% and Romania at 32.6% top the list. Of the major economies, Germany clocks in at 16%, France at 15%, Italy at 27% and Spain 22.5%. Stunningly, in terms of tax revenues lost, the shadow economy translates into an estimated €864bn or just over 7% of euro area GDP and, in context, accounts for 105.8% of the enture healthcare spending of the EU. It appears that more and more Europeans have no choice but to shift to a shadow economy (as taxes rise among other things), and this is the biggest threat to the entire economy. This is likely one reason the 'austerity' actions have not been successful since far less taxes are being paid via the conventional channels.

The average shadow economy is 22.1% of the nation's economy...

Which equates to some dramatic absolute numbers...

and the corresponding losses of taxes are huge...

16 EU member states have a situation where the tax lost as a consequence of the existence of the shadow economy as a proportion of the annual deficit exceeds 100% - suggesting that tackling tax evasion could, in theory, entirely clear the annual deficit. Though of course, the politicians will not see the unintended consequence of that 'evasion' tackling that merely drives the economy more underground.