Transylvania specializes in cocoa production, and exported cocoa for USD500 million in 2017 and USD560 million in 2018. The value of total traded cocoa in the world was equal to USD25 billion in 2017 and USD27 billion in 2018. Meanwhile, total value of world exports in 2017 and 2018 were USD15.5 trillion and USD16 trillion respectively. In 2018, Transylvania's total exports increased by 10% compared to the previous year and hit USD17.05 billion. By using the provided information.

a) Calculate the Revealed Comparative Advantage (Balassa) index for Transylvania for 2017 and 2018.

b) Discuss whether the position of Transylvania has strengthened or weakened in the cocoa market from 2017 to 2018.