Answer the question on the basis of the following data. All figures are in billions of dollars. Personal Taxes 40 Social Security Contributions 15 Taxes on Production and Imports 20 Corporate Income Taxes 40 Transfer Payments 22 US Exports 24 Undistributed Corporate Profits 35 Government Purchases 90 Gross Private Domestic Investment 75 US Imports 22 Personal Consumption Expenditures 250 Consumption of Fixed Capital 25 Net Foreign Factors Income 10 Statistical Discrepancy 0 Refer to the above data. DI is: