(a) Primary sector was the largest producing sector in 1973.
It has around 45% share in GDP because majority of population was involved in agriculture due to lack of economic development.
(b) Tertiary sector was the largest producing sector in 2003. Its contribution to GDP was around 51%.
(c) Main reason for the highest increase in GDP in tertiary sector was that due to economic development, income of people increases. It results in more demand for services like tourism, shopping, private schools and hospitals, etc.