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.
By convention, the age class is the number of 1st January days experienced by the individual. The age maximum observed was specified for each population varying from 6 to 10 years (circles).
