How are you defining "Europe"?

If you mean the EU it didn't exist back when this graph started although arguably it's predecessor did in a very different form. More countries have since joined and one, notably, has left.

If you mean the continent there are parts of it where we simply don't have records because the countries themselves have changed a lot, are generally unhelpful or flat out lie (cough Russia cough), and the boundaries themselves are open to interpretation.