Complex sentence: Although the cost of manufacturing a drug is relatively low, the cost of developing a new drug is relatively high, and the United States' high drug prices allow the U.S. pharmaceutical industry to invent a disproportionately high share of all drugs.
Split into simpler sentences: Although the cost of manufacturing a drug is relatively low, the cost of developing a new drug is relatively high. The United States' high drug prices allow the U.S. pharmaceutical industry to invent a disproportionately high (?) share of all drugs.