...
my $data = GD::Graph::Data->new(
          [["2001", "2002", "2003", "2004", "2005", "2006", "2007", "2008", "2009", "2010"],
          [ 10.2, 7.5, 4.8, 5.5, 5.5, 5.3, 4.6, 5.3, 5.7, 3.6],
          [ 9.8, 9.9, 9.8, 9.9, 9.8, 9.9, 9.8, 9.9, 9.8, 9.9]]);

...
my $graph = new GD::Graph::bars( 600, 400 );
...