Write SQL query to solve given problem: What is the average number of stars given by Oregon clients in their reviews?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(SUM(T3.Stars) AS REAL) / COUNT(T3.Stars) AS average FROM state AS T1 INNER JOIN district AS T2 ON T1.StateCode = T2.state_abbrev INNER JOIN reviews AS T3 ON T2.district_id = T3.district_id WHERE T1.State = 'Oregon'