Since it is a CSV file you could use Text::CSV like Loops mentioned or use Text::CSV_XS like so:

use strict;
use warnings;
use Text::CSV_XS;
use Data::Dumper;

my %data;

my $csv = Text::CSV_XS->new( { binary => 1 } )
  or die "Cannot use CSV: " . Text::CSV->error_diag();

while ( my $row = $csv->getline(*DATA ) ) {

    $data{ shift @{$row} } = $row;
}
$csv->eof or $csv->error_diag();

# Please print out your data as you
# specified as you wanted :)
print Dumper \%data;

__DATA__
100.1,A ,25, 36,56,89,45,36,56
25.1,B,232,565,65,56,56,48,25
103.1,C,25,5,6,9,4,5,56,889,9
10.1,D,5,6,5,8,9,8,12,23,36,6
[download]

NOTE:
Am only showing the usage of Text::CSV_XS, here, with "__DATA__", the OP would have to check the documentation to see how it used with a "file".
The desired print out is also left out for the OP.

Hope this helps.