I want to know the answer to the following question:
What is Portugal the world's leading producer of?
All the background I'm provided with is that "Since the Carnation Revolution of 1974, which culminated in the end of one of Portugal's most notable phases of economic expansion (that started in the 1960s), a significant change has occurred in the nation's annual economic growth.[citation needed]". Is that enough to answer the question?
Answer: no