Limiting it to planes produced in quantities greater than 1000 would be stupid as there are very few aircraft left to be added that meet that requirement. In addition, large production numbers are not a perfect arbiter of how significant an aircraft was. Compare the P-63 with the H8K2 'Emily', the first produced in the thousands and seeing as close to no combat as possible and the second only having 112 examples, but seeing heavy use throughout the war.