From http://www.who.int/trade/glossary/story073/en/:
The global pharmaceuticals market is worth US$300 billion a year, a figure expected to rise to US$400 billion within three years. The 10 largest drugs companies control over one-third of this market, several with sales of more than US$10 billion a year and profit margins of about 30%. Six are based in the United States and four in Europe. It is predicted that North and South America, Europe and Japan will continue to account for a full 85% of the global pharmaceuticals market well into the 21st century. Companies currently spend one-third of all sales revenue on marketing their products - roughly twice what they spend on research and development.
As a result of this pressure to maintain sales, there is now, in WHO’s words, “an inherent conflict of interest between the legitimate business goals of manufacturers and the social, medical and economic needs of providers and the public to select and use drugs in the most rational way”. This is particularly true where drugs companies are the main source of information as to which products are most effective. Even in the United Kingdom, where the medical profession receives more independent, publicly-funded information than in many other countries, promotional spending by pharmaceuticals companies is 50 times greater than spending on public information on health. [emphasis added]
(Exact date of post not clear, but $300 billion a year suggest suggests early to mid 2000s).