user: Question: What is the date settled for 40 years?
Columns: ['Suburb', 'Population (in 2008)', 'Median age (in 2006)', 'Mean household size (in 2006)', 'Area (km²)', 'Density (/km²)', 'Date first settled as a suburb', 'Gazetted as a Division Name']
Types: ['text', 'real', 'text', 'text', 'text', 'real', 'real', 'text']
Sample row: ['Chifley', 2325.0, '36 years', '2.3 persons', '1.6', 1453.0, 1966.0, '12 May 1966']
SQL:

assistant: SELECT "Date first settled as a suburb" FROM "Table" WHERE "Median age (in 2006)" = '40 years';