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Thanks in advance!
It all depends on what type of site you have. Some site 'types' may have 1/2 those figures and some may have 5-10 times those figures.
For example - forums and photo galleries would often have a similar or somewhat lower figures.
Unique original content on something that has high valued products may have many times those numbers.
If you haven't optimized ad placement, # of ads per page, and ad size and color combinations then you may be table to double or triple those numbers.
And, welcome to webmaster world :)
should I expect to see this maintained
No, absolutely not. It may be for a while, it may drop off to 10% of that in a month or it may double in six months. Don't expect anything, just be happy with what you have while you have it.
You may want to do some split testing (if you have the technical inclination) with regards to colors and placement to see which performs better. You can get some increases by experimenting, but you should probably let it go for a couple of months to at least establish more of a baseline.
But really, don't do anything critical with your life expecting your Adsense income to stay the same over the long haul.
I'd also suggest putting banners on different pages to see where they work best for you. You may be surprised as to where banners will, and won't work. Don't forget to give each banner a channel so that you can work out how it's performing.
Good luck with it!