In search of smoking guns: What makes income inequality vary over time in different countries?

Information about GDP per capita; GDP growth; total public expenditure as percent of GDP; percent public consumption; gini coefficient for equivalent disposable income; percent imports from developing countries; inflation; percent social security transfers; percent unionized; percent unemployed; female labor force participation rate; percent employed in industry; percent employed in agriculture; percent employed in service sector; percent of population aged 0-14 years; percent of population aged 15-64 years; percent of population aged 65 years or more for 16 industrialized countries during the period 1966-1994.

Purpose:

Find the reason to why income distribution change in industrialized countries.