The code is 
#!/usr/bin/perl

use strict;
use warnings;
use File::Slurp;
use Data::Dumper;

my %graph_point_hash;
my @report_graph_point = `sed -e 's/data//g' -e 's/[\<\/\>]//g' -e 's/^ *//' -e 's/* \$//' -e '/^\$/d' -e '1d;\$d' $ARGV[0]`;
my @split_graph_points;



foreach (@report_graph_point) {

        @split_graph_points = split (' ', $_);
        foreach my $graph_point (@split_graph_points) {
                $graph_point =~ s/"//g;
                my ($key, $val) = split ("=", $graph_point);
                push (@{$graph_point_hash{$key}}, "$val");
        } #foreach loop ends here

} #foreach loop ends here

print Dumper \%graph_point_hash;

XML file is 

<iostat>
  <data avgqu="0" avgrq="0" await="0" device="sdb" elapsed_time="0" r="0" rmb="0" rrqm="0" svctm="0" util="0" w="0" wmb="0" wrqm="0" />
  <data avgqu="0" avgrq="0" await="0" device="sda" elapsed_time="0" r="0" rmb="0" rrqm="0" svctm="0" util="0" w="0" wmb="0" wrqm="0" />
  <data avgqu="0.00" avgrq="0.00" await="0.00" device="sdb" elapsed_time="1" r="0.00" rmb="0.00" rrqm="0.00" svctm="0.00" util="0.00" w="0.00" wmb="0.00" wrqm="0.00" />
  <data avgqu="0.00" avgrq="58.91" await="0.09" device="sda" elapsed_time="1" r="0.00" rmb="0.00" rrqm="0.00" svctm="0.09" util="0.05" w="5.50" wmb="324.00" wrqm="35.00" />
  <data avgqu="0.00" avgrq="0.00" await="0.00" device="sdb" elapsed_time="2" r="0.00" rmb="0.00" rrqm="0.00" svctm="0.00" util="0.00" w="0.00" wmb="0.00" wrqm="0.00" />


THE OUTPUT IS

$VAR1 = {
          'w' => [
                   '0',
                   '0',
                   '0.00',
                   '5.50',
                   '0.00',
                   '2.50',
                   '0.00',
                   '489.50',
                   '0.00',
                   '0.00',
                   '0.00',
                   '0.00',
                   '0.00',
                   '242.00',
                   '0.00',
                   '0.00',
                   '0.00',
                   '5.50',
                   '0.00',
                   '4.00',