CREATE TABLE table_76082 ("Name" CLOB, "Year commissioned" FLOAT, "Gross head  ( metres ) " FLOAT, "Installed capacity  ( megawatts ) " FLOAT, "Average annual output  ( million KWh ) " FLOAT)

What is the earliest Year commissioned wiht an Average annual output greater than 58 and Installed capacity of 20?
SELECT MIN("Year commissioned") FROM table_76082 WHERE "Average annual output (million KWh)" > '58' AND "Installed capacity (megawatts)" = '20'
SELECT MIN("Year commissioned") FROM "table_76082" WHERE "Average annual output (million KWh)" > '58' AND "Installed capacity (megawatts)" = '20'