Where am I from? (accent localization)

Hi everybody,

I just recorded the text from the Speech Accent Archive (http://accent.gmu.edu/). It would be nice if you tell me, where you think I am from, when you here my accent. I used the internal microphone of my laptop, so the quality is relatively bad, but I think it's good enough for that purpose.

What should I try to improve to sound more like a native American?

This is the mp3 file:
http://www.2shared.com/file/3885435/adb313b4/accent.html

Sorry, of course I meant "American native speaker", not "native American".

You are probably German.

Why do you need to 'improve' your accent? Your English is perfectly understandable and your accent is very good. It sounds more British than American at the moment, but that's not a bad thing.