CREATE TABLE table_37643 ("Location  ( State ,  City ) " TEXT, "USN 2013" FLOAT, "BW 2013" FLOAT, "Forbes 2011" FLOAT, "Ec 2013" FLOAT, "FT 2011" FLOAT, "AE 2011" FLOAT, "CNN 2011" FLOAT, "BI 2013" FLOAT, "ARWU 2012" FLOAT)

What is the USN 2013 ranking with a BW 2013 ranking less than 1000, a Forbes 2011 ranking larger than 17, and a CNN 2011 ranking less than 13?
SELECT SUM("USN 2013") FROM table_37643 WHERE "BW 2013" < '1000' AND "Forbes 2011" > '17' AND "CNN 2011" < '13'
SELECT SUM("USN 2013") FROM "table_37643" WHERE "BW 2013" < '1000' AND "CNN 2011" < '13' AND "Forbes 2011" > '17'