Where do I edit the number of products in the category view drop down?

[bluetail2011]

VM 2.0.6 / Joomla 2.5.4

Hi all,

I'm sure there's a very simple answer to this, but I can't seem to find it. In the category view there is a drop-down in the top-right corner of the page, where you can select to show '1, 2, 3, 4, 5, 10, 20' products.

I would like to change that to '1, 5, 10, 20, 50, all'. What file do I have to edit to do this?

thanks,

Peter