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.
Includes those recorded during (a) all years combined (1980–2015) and during the winters of (b) 2009–2010, (c) 2010–2011, (d) 2013–2014, and (e) 2014–2015.
