Research from Sweden's University of Gothenburg found that the 3,000 consumers surveyed in Beijing and Guiyang used an average of 21 new plastic bags per week before China began requiring stores to charge some fee in June 2008. After the ordinance, they used 49% fewer bags and almost half of them were re-used.

In Washington, D.C., stores began charging a nickel in January for each disposable bag and managers have since reported a drop in bag sales. Ireland's plastic bag tax, begun in 2002, has reduced usage to about 20 bags per year per shopper, compared with 330 bags per year before the fee.

(Source: Study: Plastic bag fee cuts bag use in China by half [USA Today])