According to the British Foreign Office, Netherlands and Canada both have the same terrorism threat level (3).
If you want to go to Europe with a low terrorism threat, then Iceland, Ireland, Switzerland, Poland, Estonia, Lithuania, Latvia, Czech Republic, Slovenia and Moldova all have a terrorism threat level of 1 (an attack is unlikely)
In case you were wondering, both the US and the UK have a threat level of 4 (an attack is highly likely) right now.