The global market for e-cigarettes and e-liquids almost doubled, to $6 billion, from 2013 to 2014, a new report finds. During that same period, cigarette sales decreased 0.4 percent, according to CBS News.

The report on e-cigarettes and e-liquids was issued by the market research firm Euromonitor International. The United States, with $2.8 billion in sales last year, accounts for about half of all global sales. Demand for e-cigarettes is also strong in Europe, especially the United Kingdom, Italy, Poland and France.

Shane MacGuill, a tobacco analyst at Euromonitor, says the growth in e-cigarettes is partly fueled by the perception that they are healthier than traditional cigarettes. Because they are not yet taxed at the same high rate as cigarettes, they are significantly less expensive, he added.

An online poll released earlier this month found about 10 percent of U.S. adults use e-cigarettes, significantly higher than a recent government estimate of 2.6 percent.

The Reuters/Ipsos poll found about 15 percent of those under age 40 use e-cigarettes. Almost 70 percent of current e-cigarette users started in the last year.

Many e-cigarette users also smoke conventional cigarettes, the poll found. About 80 percent said using e-cigarettes was “a good way to help people quit smoking.” Almost half of users said they started using the devices because of friends or family, and almost 40 percent said they liked being able to smoke indoors, as well as the lower cost over time.

Last month a group of experts convened by the U.S. government concluded there is not enough evidence to support using e-cigarettes to quit smoking. The U.S. Preventive Services Task Force said medicines, including nicotine replacement products, along with behavior modification programs, are more effective.