Write SQL query to solve given problem: What percentage of businesses in the Northwest US have forecasted annual sales of above 300,000?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(SUM(CASE WHEN T1.SalesQuota > 300000 THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T1.BusinessEntityID) FROM SalesPerson AS T1 INNER JOIN SalesTerritory AS T2 ON T1.TerritoryID = T2.TerritoryID WHERE T2.CountryRegionCode = 'US' AND T2.Name = 'Northwest'