user: Question: How many items were listed under world rank under the nation of Nigeria?
Columns: ['African rank', 'World rank', 'Nation', 'GDP per capita', 'Total GDP world rank']
Types: ['real', 'real', 'text', 'text', 'real']
Sample row: [1.0, 41.0, 'Equatorial Guinea', '$16,507', 113.0]
SQL:

assistant: SELECT COUNT("World rank") FROM "Table" WHERE "Nation" = 'Nigeria';