I am using `RCurl` in R to try and download data from a website, but I'm having trouble finding out what URL to use. Here is the site: 

<http://www.invescopowershares.com/products/holdings.aspx?ticker=PGX>

See how in the upper right, above the displayed sheet, there's a link to download the data as a `.csv` file? I was wondering if there was a way to find a regular HTTP address for that `.csv` file, because `RCurl` can't handle the Javascript commands.