assume an economy has grown by 4% per year over the past 30 years. during the same period, the labor force has grown by 1% per year and the quantity of physical capital has grown by 5% per year. each 1% increase in physical capital per worker is estimated to increase productivity by 0.4%. assume that human capital has not changed during the past 30 years. how much has technological progress contributed as a percentage of productivity growth?