I think that you meant $sum*100 in the end...
:)

Here is a small improvement. It adds a '/' to directory names,

.
.
.
  ($size, $inode)=split;
  $inode .= "/" if (-d $inode);
  chop($size);
.
.
.
[download]

also, the printf should be changed. Instead of "%2.2f" you probably meant "%5.2f". The first digit is the total number of digits, including the period.