Happy Earth Day, everybody! More than a billion people in 192 countries take part in Earth Day activities, according to Earth Day network.

By the numbers:

4.43 – Pounds of "municipal solid waste" generated per person in the United States each day in 2010.

34.1 – Percent of "municipal solid waste" that ends up getting recycled.

43,271.4 – Percent change in CO2 emissions in Namibia since 1980, the highest in the world. (Not a typo!)

55.43 tonnes – CO2 emissions per capita in Qatar for 2007, the highest in the world.

5 – Percent of Americans who are vegetarian.

16,500 – Number of "Energy Star" certified buildings in the United States.

6 – Cities in California on the list of Top 25 Cities in the United States with the most "Energy Star" certified buildings.

8 – Cities in California in the Top 10 on the list of the Most Ozone-Polluted Cities in the United States.

7 – Number of different SPI Resin Identification codes for recycling on plastic goods.

39 – States with laws regulating the use of these codes on 16 oz bottles.

35 – Percent of hybrid car owners who buy another hybrid when they get a new car.

2.4 – Percent of the "new vehicle market" claimed by hybrid cars in 2011.

81 – Percent who switched regular light bulbs with energy-efficient compact fluorescent bulbs.

70 – Percent who use reusable grocery bags instead of plastic or paper bags at the store.

1.2 million – Homes in the United States that use solar power.