The data you requested are contained in these files:

    icec.1981.nc
    icec.1982.nc
    icec.1983.nc
    icec.1984.nc
    icec.1985.nc
    icec.1986.nc
    icec.1987.nc
    icec.1988.nc
    icec.1989.nc
    icec.1990.nc
    icec.1991.nc
    icec.1992.nc
    icec.1993.nc
    icec.1994.nc
    icec.1995.nc
    icec.1996.nc
    icec.1997.nc
    icec.1998.nc
    icec.1999.nc
    icec.2000.nc
    icec.2001.nc
    icec.2002.nc
    icec.2003.nc
    icec.2004.nc
    icec.2005.nc
    icec.2006.nc
    icec.2007.nc
    icec.2008.nc
    icec.2009.nc
    icec.2010.nc
    icec.2011.nc
    icec.2012.nc
    icec.2013.nc
    icec.2014.nc
    icec.2015.nc