จำนวนครั้งที่สถานที่จัดงานตั้งอยู่ในสหรัฐอเมริกา ?ไม่จำเป็นต้องใช้โต๊ะทั้งหมด
what were the total number of times the venue was located in the united states ?It is not neccessary to use all the tables.
 table_204_450:  id [ number]  "year" [ number]  "competition" [ text]  "venue" [ text]  "position" [ text]  "event" [ text]  "notes" [ text] 
SELECT COUNT(*) FROM table_204_450 WHERE "venue" = 'united states'