user: Question: What is the number of 1991 populations named Bečej?
Columns: ['Urban settlement', 'Cyrillic Name', 'City / municipality', 'District', 'Population (1991)', 'Population (2002)', 'Population (2011)']
Types: ['text', 'text', 'text', 'text', 'real', 'real', 'real']
Sample row: ['Bač', 'Бач', 'Bač', 'South Bačka', 6046.0, 6087.0, 5399.0]
SQL:

assistant: SELECT "Population (1991)" FROM "Table" WHERE "City / municipality" = 'Bečej';