or 1.5% versus FY2016. Primary receipt categories included individual income taxes ($1,587billion or 48% of total receipts), Social Security/Social Insurance taxes ($1,162billion or 35%), and corporate taxes ($297billion or 9%). Other revenue types included excise, estate and gift taxes. FY 2017 revenues were 17.3% of gross domestic product (GDP), versus 17.7% in FY 2016. Tax revenues averaged approximately 17.4% GDP over the 1980–2017 period. The federal budget deficit (i.e., expenses greater than revenues) was $665billion in FY2017, versus $585billion in 2016, an increase of $80billion or 14%. The budget deficit was 3.5% GDP in 2017, versus 3.2% GDP in 2016. The budget deficit is forecast to rise to $804billion in FY 2018, due significantly to the Tax Cuts and Jobs Act and other spending bills. An aging country and healthcare inflation are other drivers of deficits and debt over the long-run. Debt held by the public, a measure of national debt, was approximately $14.7trillion or 77% of GDP in 2017, ranked the 43rd highest out of 207 countries. This debt, as a percent of GDP, is roughly equivalent to those of many western European nations. Business culture A central feature of the U.S. economy is the economic freedom afforded to the private sector by allowing the private sector to make the majority of economic decisions in determining the direction and scale of what the U.S. economy produces. This is enhanced by relatively low levels of regulation and government involvement, as well as a court system that generally protects property rights and enforces contracts. Today, the United States is home to 29.6 million small businesses, thirty percent of the world's millionaires, forty percent of the world's billionaires, and 139 of the world's 500 largest companies. From its emergence as an independent nation, the United States has encouraged science and innovation. In the early 20th century, the research developed through informal cooperation between U.S. industry and academia grew rapidly and by the late 1930s exceeded the size of that taking place in Britain (although the quality of U.S. research was not yet on par with British and German research at the time). After World War II, federal spending on defense R&D and antitrust policy played a significant role in U.S. innovation. The United States is rich in mineral resources and fertile farm soil, and it is fortunate to have a moderate climate. It also has extensive coastlines on both the Atlantic and