The National Bureau of Economic Research’s TAXSIM model allows you to calculate tax liabilities for a given individual in different years. Navigate to https://users.nber.org/~taxsim/taxsim27/ and fill in the blanks to “construct” two individuals—a lower-income individual with $22,000 in earned income and a higher-income individual with $82,000 in earned income. Assume that both individuals are 40-year-old single parents of two children aged 14 and 15, and that they do not own homes, have no child care expenses, and earn no dividend or capital gains income. Use the model to calculate these individuals’ federal (effective) marginal tax rates and federal income tax liability in 1993, 1998, 2008, and 2018. Explain the pattern you find.