user: Question: How many prefectures have a population density of 16 people/kilometers squared?
Columns: ['Number in map', 'Prefecture', 'Area (km²)', 'Population (2001)', 'Pop. density (/km²)']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['46', 'Aetolia-Acarnania', '5460.888', 224429.0, '41.10']
SQL:

assistant: SELECT COUNT("Pop. density (/km²)") FROM "Table" WHERE "Number in map" = '16';