user: Question: Name the number of countries that have the US dollar
Columns: ['Currency', 'Country', 'Generic Name or Nickname', 'Rating ( S&P / Moodys )', 'Negotiable debt at mid-2005 ( US dollar bn equivalent)', 'Government financial liabilities as % of GDP (end 2003 - source : OECD )', 'Issuer', 'Internet site']
Types: ['text', 'text', 'text', 'text', 'real', 'text', 'text', 'text']
Sample row: ['Yen', 'Japan', 's JGB', 'AA-/A2', 6666.0, '157.5%', 'Ministry of Finance (MoF)', 'Site']
SQL:

assistant: SELECT COUNT("Country") FROM "Table" WHERE "Currency" = 'US dollar';