Fig. 8.
Annual trends of the selected topics. Note: The annual trends depicted in this figure illustrate the temporal evolution of the selected topics between 2015 and 2022. Source: Created by the authors.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.