From the Summary: "This report describes the federal tax structure and system in effect for 2019. The report also provides selected statistics on the tax system as a whole. Historically, the largest component of the federal tax system, in terms of revenue generated, has been the individual income tax. For fiscal year (FY) 2019, an estimated $1.7 trillion, or 50% of the federal government's revenue, will be collected from the individual income tax. The corporate income tax is estimated to generate another $216 billion in revenue in FY2019, or just over 6% of total revenue. Social insurance or payroll taxes will generate an estimated $1.2 trillion, or 36% of revenue in FY2019. For 2019, it is estimated that revenues will be 16.1% of gross domestic product (GDP), slightly below the post-World War II average of 17.2% of GDP."
CRS Report for Congress, R45145
Congressional Research Service: https://crsreports.congress.gov/