Where to get free or cheap cup of coffee on National Coffee Day

Go ahead, have another cup of coffee. This week's mug runneth over with days devoted to the beverage that wakes up nations and keeps industries humming.

According to Internet sages and the arbiters of faux holidays, September 29 is Coffee Day (also known as National Coffee Day or International Coffee Day).

The origins of this day of caffeinated celebration are largely unknown, but who needs an origin story to justify that second, third or fourth cup?

Coffee purveyors are offering freebies to mark the occasion.

Among them, Dunkin' Donuts is selling medium-sized cups of coffee for 66 cents -- a nod to their 66th anniversary.

Krispy Kreme is upping the ante with a free glazed doughnut and a free 12-ounce cup of coffee at participating locations in the US.

McDonald's is also giving away a small hot or iced coffee if you present the deal that's available today in their mobile app.

While there is no free coffee at Starbucks, the company is donating a coffee tree to a farmer in need for every cup of Mexico Chiapas coffee purchased.

According to the intergovernmental International Coffee Organization, October 1 2015 was the "first official" International Coffee Day.

Statistics suggest that coffee-loving Finns will outdo the rest of the world.

Finland is No. 1 in the world for coffee consumption per capita, according to data collected by market research provider Euromonitor International. On average, each person in Finland consumed 9.9 kilograms (21.8 pounds) of coffee in 2014.

Sweden, the Netherlands, Norway and Slovenia round out the top five coffee-consuming nations.

The United States didn't even break the top 10, ranking 25th for coffee consumption in 2014. Americans consumed 3.1 kilograms (6.8 pounds) of coffee per capita last year, the same amount as the citizens of France.

Italians consumed slightly more: 3.4 kilograms (7.5 pounds), coming in at No. 21 on the global list.