Well me ol china.
You are the one who thinks the UK's success after the 70's was down to being a peripheral member of the EU club, when it is patently obvious that it was Thatcher's reform process that mended the UK economy.
So, how can you talk about how to measure performance, when your fundamental premise is flawed?
The EU is failed. The smart people knew this day would arrive. Thankfully, we had just enough smart politicians around at the time, who kept us out of full membership.
And finally. If we were outside the EU now, would we as a country be looking to join this dysfunctional club? That is the question. If your answer to the question is no, then your argument about staying in completely falls apart.