Use the line graph shown. The graph shows annual cigarette consumption (in billions) for the United States for the years 1900 to 2010.

Cigarette Consumption in the United States

Billions of cigarettes

700

600

500

400

300

200

100

0

1900 1920

1940

1960 1980

Year

2000

The year(s) in which 400 billion cigarettes were smoked:

Estimate the year or years in which 400 billion cigarettes were smoked. If there is more than one answer, separate them with commas.

DO

2010

X