Figure 2.
The bar chart displays number of studies on the vertical axis and publication year from 2003 to 2025 on the horizontal axis. The number of studies remains low in early years with small increases and fluctuations until around 2011. From 2012 onwards, the values gradually increase with minor variations. After 2018, the number of studies rises more sharply. The highest value appears in 2025, indicating a continued upward trend over time.Literature development over time
Note(s): This figure shows the annual distribution of the 209 empirical RD studies published between 2003 and 2025
Source: Authors’ own work