Wait.... 'almost exclusively' ??? You have to be having a laugh with that statement. The US, as a single country, produces the most pharmaceutical advancements compared to other countries. But you are seriously ignorant to the world of research if you think it is even close to the majority of advancements. There are so many other countries heavily involved with that have far less GDP and population number (Germany, France, UK, Switzerland...).

To compare US and UK.

US has a population of 325 million, and produced 36% of new pharmaceutical innovations UK has a population of 66 million and produced 10.4% of new pharmaceutical innovations

Your population is about 5 times larger although only produces about 3.5x as much of a share of new drugs.

The same can be said of most of the other countries producing new drugs, good example is Switzerland who produce 3% of the new drugs with a population 1/40 the size of the US.

When looking at medical research you guys achieve more because you have more people, its that simple. If you scale it to other countries size you actually perform way under the average.