Audio File Sizes in Audacity

I just started checking in my data folder at the ASP.NET Podcast Show #8 that I am putting together.  When I save the files in then native format of Audacity, the file size is 533 megabytes.  When I save it to an mp3 file, the file size is 15.4 megabytes.  Wow, what a difference.  Compression is good.

Wally