user: Question: What is the Year commissioned of the power station with a Gross head of 60 metres and Average annual output of less than 59 million KWh?
Columns: ['Name', 'Year commissioned', 'Gross head (metres)', 'Installed capacity (megawatts)', 'Average annual output (million KWh)']
Types: ['text', 'real', 'real', 'real', 'real']
Sample row: ['Deanie', 1963.0, 113.0, 38.0, 92.0]
SQL:

assistant: SELECT "Year commissioned" FROM "Table" WHERE "Gross head (metres)" = 60.0 AND "Average annual output (million KWh)" < 59.0;