| Country | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2015 | 2016 | 2017 |
|---|
| Belgium | 23,900 | 25,300 | | 29,000 | 29,100 | 30,600 | 31,100 | 33,000 | 36,200 | 37,400 | 36,800 | 37,800 | 38,200 | 38,500 | 37,800 | 43,600 | 44,900 | 46,600 | | Finland | 21,000 | 22,900 | | 26,200 | 27,400 | 29,000 | 31,000 | 33,700 | 36,000 | 36,900 | 34,100 | 35,400 | 36,700 | 37,000 | 35,900 | 40,600 | | 44,500 | | Germany | 22,700 | 23,400 | | 26,600 | 27,600 | 28,700 | 30,100 | 31,900 | 34,100 | 35,400 | 34,200 | 35,700 | 38,400 | 39,700 | 39,500 | 46,900 | 48,200 | 50,800 | | Portugal | 15,300 | 15,800 | | 18,000 | 18,000 | 17,900 | 19,000 | 19,800 | 21,800 | 22,200 | 22,500 | 23,000 | 23,700 | 23,800 | 22,900 | 27,800 | 28,500 | 30,500 | | United States | 33,900 | 36,200 | 36,300 | 37,600 | 37,800 | 40,100 | 41,600 | 44,000 | 45,800 | 46,900 | 46,000 | 47,200 | 49,000 | 50,700 | 52,800 | 55,800 | 57,300 | 59,800 |
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