WASHINGTON (MarketWatch) — The minimum wage remains a hot topic.

With the 2016 presidential election looming, several top Democrats this week unveiled a proposal to boost the U.S. minimum wage by 66% — to $12 an hour. And a newly announced White House candidate, independent Sen. Bernie Sanders of Vermont, has said a $15 ”livable” wage might be reasonable.

What is the federal minimum wage? How many earn the minimum or less? Who are they? Will it really help a lot of people? Here are the facts.

Nationwide

• $7.25 — The federal minimum wage, last raised in 2009. The law applies to most employees with a few exceptions, such as workers like waiters or bartenders who also earn tips.

• 3.3 million — The number of people in 2013 who earned at or below the federal minimum wage, according to the most recent government data available.

• 2.4% — The share of total U.S. workers in 2013 who earned at or below the federal minimum wage.

• 1.01 million — The number of minimum-wage employees who work full time (35 hours or more).

• 0.8% — The share of full-time U.S. workers earning at or below the minimum wage.

By race and sex

• 77.4% — The share of workers earning the minimum or less who are white.

• 62.4% — The share of minimum-wage workers who are women.

• 15.2% — The share of blacks who earn the minimum or less. (The government lacks precise data on those of Latino or Hispanic descent. Some may fall under other racial categories.)

By state and region

• 29 — The number of states that set a minimum wage above the federal level (see your state’s minimum here).

• 46.4% — Share of federal minimum-wage workers in the South, the region with the highest concentration. The West is the area with the lowest share: 12%.

• 12.1% — The share of people who earned the federal minimum or less in 2013 who live in Texas. Next in line were Pennsylvania at 5.7%, Florida at 5.5% and New York at 5.4%.

By age and marital status

• 50.4% — Share of minimum-wage workers between ages 16 to 24. Or 1.66 million workers.

• 49.6% — Share of minimum-wage workers 25 or older. Or 1.64 million workers.

• 910,000 — Workers earning the federal minimum who have never married.

• 684,000 — Married people still living with their spouse who earn the federal minimum.

• 411,000 — Minimum-wage workers once married whose current status is unclear.

• 111,000 — The number of seniors 65 or older earning the federal minimum.

By occupation and education

• 46.7% — Share of minimum-wage workers in food preparation and related “hospitality” industries. No other sector comes close.

• 29.7% — Share of high-school graduates who earn the federal minimum.

• 28.1% — Share of those lacking a high school diploma earning the minimum wage.

• 7.9% — Share of minimum-wage earners with a college degree.