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Utopia doctors immunize children against measles, a highly contagious and potentially deadly virus. The demand and supply curves for the immunization are given by the following equations. Demand: Q =200 -P thousand immunizations per year Supply: Q =2P - 20 thousand immunizations per year but the social marginal benefit (SMB) is given by the following equation Q =200 - 0.8 x SMB thousand immunizations per year and the private marginal cost and social marginal cost are identical. 18. If the market is left unregulated, the market equilibrium level of immunization is [ Answer18 ] thousand immunizations per year. 19. The total economic surplus to the society from the market equilibrium level of immunization is [ Answer19 ] thousand dollars per year. 20. The socially efficient level of immunization is [ Answer20 ] thousand immunizations per year. 21. The total economic surplus to the society at the socially efficient level of immunization is [ Answer21 thousand dollars per year. 22. Suppose the government decides to address the inefficiently low rate of immunization by paying doctors for every immunization. That is, the cost of immunization to the general public is zero. The total economic surplus to the society with such publicly-paid immunization is [ Answer22 ] thousand dollars per year. 23. If, instead, the government applies a per unit subsidy on immunization to achieve the socially efficient level, it should implement a per unit subsidy of [ Answer23 ] dollar(s) per immmunization. 24. This per unit subsidy will cost the government a total of [ Answer24 ] thousand dollars of subsidy expenditure per year