Fig. 2

Distribution of included studies by countries’ disease and year. Data from 55 studies are included in this figure. Because of the relatively large number of trials in China and Iran, bubble plots were used for presentation. For trials in the ‘recruiting’ status, we included the time that the trial started. For trials in the ‘complete’ status, we included the time that the trial was completed. In China, the size of a scatter plot is the trial’s numbers. In Iran, the size of a scatter plot is the subject number because the disease was exclusively multiple sclerosis