You'll have to do the sorting yourself, but here's what I came up with (just a quick hack):

#!/usr/bin/perl -w

foreach (<DATA>) {
    next if /^#/;  # Oops!  Forgot this the first time :(
    my @results = split;
    $type = $1 if $results[3] =~ /(\.\w+)$/;
    $code = $results[4];
    $output{$type}{$code}++;
}
foreach $type_key (keys %output) {
    foreach $code_key (keys %{$output{$type_key}}) {
        print "$type_key\t$code_key\t$output{$type_key}{$code_key}\n";
    }
}

__DATA__
00:00:29 192.168.20.50 GET /Plastic/ProductTop.html 200
00:00:29 192.168.20.50 GET /Plastic/images/ProductNavTopRt.jpg 304
00:00:29 192.168.20.50 GET /plastic/ProductNav.html 200
00:00:29 192.168.20.50 GET /plastic/images/ProductNav1b.jpg 304
00:00:29 192.168.20.50 GET /main.html 202
[download]

The output was as follows:

.html   200     2
.html   202     1
.jpg    304     2
[download]

Cheers,
Ovid

Update: I'm seeing responses to this node which are almost, but not quite correct. If you read the question carefully, you'll notice that the type and code are not synonymous. You can't just lump them together and ++, nor can you simply count the instances of each type. Each type can have multiple codes and it's the instances of each code per type that the poster as looking for.