You should give Text::ASCIITable a try:

#!/usr/bin/perl 
use strict;
use warnings;

use Text::ASCIITable;
my $table = Text::ASCIITable->new(
                {headingText => 'Sales per Year'}
                );
$table->setCols('Year', 'Sales');

$table->alignCol('Sales' => 'right');
$table->setColWidth('Sales' => 10);

$table->addRow(2005, 3000.00);
$table->addRow(2006, 4000.00);
$table->addRow(2007, 3500.00);
$table->addRow(2008, 5800.00);
$table->addRowLine;
$table->addRow('Average',4075.00);
print $table;
[download]

Output

.-----------------.
|  Sales per Year |
+---------+-------+
| Year    | Sales |
+---------+-------+
|    2005 |  3000 |
|    2006 |  4000 |
|    2007 |  3500 |
|    2008 |  5800 |
+---------+-------+
| Average |  4075 |
'---------+-------'
[download]

Hope this helps.
Thomas