Complex sentence: Up until the last quarter of 1944,756 Heinkel He 111s had been built, while Junkers produced 3,013 Ju 88s, of which 600 were bomber versions.
Split into simpler sentences: Up until the last quarter of 1944,756 Heinkel He 111s had been built. While Junkers produced 3,013 Ju 88s, of which 600 were bomber versions.