Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Conference | Date | Place | attendance | Archive of presentations |
| --- | --- | --- | --- | --- |
| Wikimania 2005 | August 5–7 | Frankfurt, Germany | 380 | slides, video |
| Wikimania 2006 | August 4–6 | Cambridge, United States | 400 | slides and papers, video |
| Wikimania 2007 | August 3–5 | Taipei, ROC (Taiwan) | 440 | Commons gallery |
| Wikimania 2008 | July 17–19 | Alexandria, Egypt | 650 | abstracts, slides,video |
| Wikimania 2009 | August 26–28 | Buenos Aires, Argentina | 559 | slides, video |
| Wikimania 2010 | July 9–11 | Gdańsk, Poland | about 500 | slides |
| Wikimania 2011 | August 4–7 | Haifa, Israel | 720 | presentations, video |
| Wikimania 2012 | July 12–15 | Washington, D.C., United States | 1,400 | presentations, videos |
| Wikimania 2013 | August 7–11 | Hong Kong | 700 | presentations, videos |
| Wikimania 2014 | August 6–10 | London, United Kingdom | N/A |  |
Question:
how many wikimanias have been held in the usa?
Answer:
2