June 28 (Reuters) - The U.S. Supreme Court's ruling on Thursday arose from President Barack Obama's 2010 healthcare law, the most sweeping healthcare legislation since the government Medicare and Medicaid programs of the 1960s.

The law, which constituted the $2.6 trillion U.S. healthcare system's biggest overhaul in nearly half a century, sought to provide health insurance to more than 30 million previously uninsured Americans and to slow down soaring medical costs.

Here are 10 facts about healthcare in the United States, the country with the world's largest economy.

Annual healthcare spending is $2.6 trillion, or $8,402 per person and 17.9 percent of the economy. Over the coming decade, rising healthcare costs are expected to make spending balloon to $4.8 trillion, or one-fifth of gross domestic product, according to the U.S. Centers for Medicare and Medicaid Services.

About 50 million people are without any health insurance in the United States, a country with a population of more than 310 million, according to the U.S. Census Bureau.

The Obama administration says the uninsured create $43 billion in uncompensated healthcare costs each year and that the cost-shifting represents about 1.7 percent of total spending on healthcare. For a family of four, that translates to an estimated increase of $1,000 in annual health insurance premiums.

The Affordable Care Act, a 2,700-page piece of legislation signed into law by Obama on March 23, 2010, aimed to extend coverage to more than 30 million uninsured people.

The law contained a two-pronged plan to expand health coverage. It envisioned new state insurance markets in which people with family incomes of up to nearly $90,000 would be able to buy private insurance at government subsidized prices. It also called for expanding the Medicaid program for the poor to cover people with annual family incomes of nearly $30,000, or 133 percent of the poverty line as defined by the federal government.

The "individual mandate," the law's most contentious provision, required most Americans to obtain health coverage by 2014, when the legislation was due to take full effect. Those who did not comply would be forced to pay a financial penalty to be phased in through 2016. In 2014, the penalty for individuals was set at $95, or 1 percent of taxable income, whichever was greater. By 2016, it was set at $695, or 2.5 percent of income. The law exempted illegal immigrants, the very poor, Native Americans, certain religious groups and prison inmates.

Twenty-six of the 50 U.S. states challenged the law on grounds it exceeded the federal government's constitutional authority. The challenge has also been brought by the National Federation of Independent Business and individuals who do not want to buy insurance.

Before the case reached the Supreme Court, four U.S. appeals courts ruled on the individual mandate - three of the four rejecting state challenges. The fourth ruled the mandate unconstitutional but let the rest of the law stand.

The high court heard oral arguments on March 26, 27 and 28 that lasted a combined six hours and 26 minutes.

The U.S. healthcare system is highest in spending and 31st in providing healthcare coverage to its people among the 34 members of the Paris-based Organization for Economic Cooperation and Development, the OECD says. 

(Reporting by David Morgan, Joan Biskupic and James Vicini)

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