When comparing the composition of world trade in the early 20th century to the early 21st century, we find major compositional changes. These include a relative decline in trade in agricultural and primary-products (including raw materials). How would you explain this in terms of broad historical developments during this period?

When comparing the composition of world trade in the early 20th century to the early 21st century, we find major compositional changes. These include a relative decline in trade in agricultural and primary-products (including raw materials). How would you explain this in terms of broad historical developments during this period?