Fig. 1From: Current globalization of drug interventional clinical trials: characteristics and associated factors, 2011–2013The change of drug intervention clinical trials by phase, sponsor type and age groups in 2011–2013 (a) phases, (b) sponsor types, (c) age groups. Y left axis indicates the number of clinical trials and Y right axis indicates the proportion of clinical trials. Each pattern designates the registration year of clinical trials; 2011, 2012, 2013 Back to article page