The size (in bytes) of games have been growing over time. There are probably many factors contributing to this: trailer/cut scene videos being bundled with the game, more and higher-quality audio, multiple levels of detail being used, etc.

What I'd really like to know is how the size of 3D models and textures that games ship with have changed over time. For example, if one were to look at the size of meshes and textures for Quake I (1996), Quake II (1997), Quake III: Arena (1999), Quake 4 (2005), and Enemy Territory: Quake Wars (2007), I'd imagine a steady increase in file size. Does anyone know of a data source for numbers like this?