Table 2. The centrality share of the US in global drug innovation network.

Drug coverage	Periods	Degree	Betweenness	Closeness	Eigenvector
Total new drugs	1996–2000	26.47%	56.96%	5.11%	94.50%
	2001–2005	28.00%	68.76%	5.11%	90.77%
	2006–2010	16.44%	35.53%	5.01%	86.15%
NME	1996–2000	29.17%	63.83%	4.90%	88.11%
	2001–2005	24.00%	60.42%	4.95%	88.13%
	2006–2010	22.50%	55.02%	5.07%	80.37%

Note: The percentages in the cell refer to the share of the centrality of the US in total sum of relative centrality of all countries in global innovation network of specific drug coverage during specific time periods.