You can't even measure it cleanly. It was so isolated and its currency wasn't even convertible, but by most measures Japan and West Germany had larger economies with far, far, far better living standards. Go to per-capita level equivalents and you'd be hard pressed to find it higher than any western developed country. Even economic basket-case countries in South America often had better living standards.

North Korea is sending things into space. You can't measure a country on its isolated accomplishments, even if they're impressive.