Figure 2
A bar chart presents the number of papers published per year from 2000 to 2024 on the horizontal axis, with frequency on the vertical axis. Very low publication activity is shown in the early years, with single papers appearing before 2008. Publication counts increase after 2009, with multiple years showing between 4 and 6 papers. The highest frequency shown is 6 papers, occurring in several years during the mid and later period of the timeline. The lowest frequency is 1 paper, observed in the earliest years. Overall, the chart shows a general increase in publication frequency over time with fluctuations in later years.Number of papers per year