SQL如何限制BOTTOM x行（PostgreSQL）

I have a query like:

我有一个查询:

SELECT 
EXTRACT(WEEK FROM j.updated_at) as "week",  count(j.id)  
FROM  jobs    
WHERE  
EXTRACT(YEAR FROM j.updated_at)=2009   
GROUP BY EXTRACT(WEEK FROM j.updated_at)  
ORDER BY week
SELECT 
EXTRAC