Remember the Greek/eurozone debt crisis? That's what the big spike is. Now, here we are. Greek bonds are nearing their lowest levels ever.
The only explanation is that people are seeking the safest form of assets in government bonds and Central Banks are becoming more helpful managing debt and supporting their countries.
I share this as an observation that is shaping the world and the economy picture. It also is potentially showing the strength of the Eurozone and the way the countries are coming together. Pay attention to the EURUSD or European assets in these countries. If they are indeed balancing their budget, have their fiscal house in order, and the central banks are willing to support them, Europe could be ready for some more strength.