First, take a look at the graph of how Public sector debt has increased. It was incredibly stable from 1995 to 2007, increasing from just under €300 billion to less than €400 billion. But then, starting in in 2008, debt levels have tripled to over €1.1 trillion at the end of 2016.
First, over the period 1995-2016, debt levels increased by €811,348 million, an average of €38,636 million per year. But note that Spain actually decreased its debt levels in 2003, 2006 and 2007
The amount paid by Spain's taxpayers as interest on that debt totals €509,730 million. It was less than €20 billion a yaer from 2002 to 2009 but has now been substantially over €30 billion a year for the past 5 years.
The amount paid in interest charges averages 2.9%, which, when you compare that figure with the value of 14.5% of GDP corresponding to taxes in Italy provided by the World Bank, means that roughly 20% all Spain's taxes gets used to pay the interest on Public sector debt.
This is frankly criminal. As with all European Union governments, the Maasstrict and Lisbon treaties oblige governments to borrow from the financial markets - essentially commercial banks. But, because of the way that banks work, they don't have to have pre-existing money to buy Spanish Government bonds - they can just invent the money out of thin air, and then sit back and enjoy the benefits of getting billions of interest payments every year, or flog the bonds to third party investors, including US and Canadian Pension Funds.
What would a typical Spanish Citizen say if he or she found out that a substantial proportion of their taxes gets used to pay for pensions in the US? Would there be a revolution? I think there should be.