Annual growth in total U.S., U.S. NIH-funded, and relative NIH-funded cardiovascular research articles, 1996–2006.

All U.S. and NIH-funded U.S. growth rates are expressed in terms of articles per year, with relative growth expressed as a percentage of the 1996 level. The proportional growth in NIH-funded articles is expressed as the annual change in the ratio of NIH-funded to all articles, e.g. growth from 30% NIH-funded in 1996 to 41% NIH-funded in 2006 corresponds to a yearly growth of approximately 0.01, or 1 percent per year. Figures normalized to 1996 for this proportion are also depicted. Insufficient numbers of phase-type clinical trials were published to allow meaningful analysis of trend for these methodologies.