As recently as 1991, 80 per cent of industry-sponsored drug trials in the United States were conducted in university hospitals. Today, with pressures to bring drugs to market quickly, more than 70 per cent of the trials are conducted in private "contract research organisations" (CROs) to accelerate every phase of drug development. "Volunteering" for clinical trials has become a new occupation. The best-paying studies are longer, in-patient trials that may involve invasive procedures. The subjects are usually unemployed, college students, contract workers, ex-cons, or young people who require money. This has produced a community of "guinea-pigging" semi-professional research subjects, who enrol in one study after another. Most are involved in Phase I trials and cannot expect any benefit in return for the risks. "... their reason for taking the drugs is no different from that of the clinical investigators who administer them, and who are compensated handsomely ... This raises an ethical question: what happens when both parties involved in a trial see the enterprise primarily as a way of making money?"