Figure 2.
Development of the number of items in the database. The development of the item numbers in the database shows a continuous increase. The numbers in brackets indicate the increase per year.
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.