Fieldwork date | US | Canada* | Australia | UK |
---|---|---|---|---|
Jun 2004 – Dec 2004 (Wave 3) | 5.4 | 0 | 0 | 0 |
Oct 2005 – Jan 2006 (Wave 4) | 7.3 | 100 | 0 | 0 |
Oct 2006 – Feb 2007 (Wave 5) | 11.9 | 100 | 0 | 0 |
Sep 2007 – Feb 2008 (Wave 6) | 23.7 | 100 | 0 | 0 |
Jun 2009 – Dec 2009 (Wave 7) | 45.7 | 100 | 0 | 0 |
Jul 2010 – Jun 2011 (Wave 8) | 96.8 | 100 | 100 | 0 |