From the income perspective, GDP represents the total income derived from the production of goods and services that can be earned by residents or non-residents. In a highly open economy, economic activities engaged by residents outside the economy and those engaged by non-residents within the economy are more intensified; hence, the discrepancy between the value of GNI and GDP tends to become wider. Moreover, GNI data are useful reference to the research on income of residents, investment and domestic demand.