this is a great post and I would like to return the favor:
So far my app made it to #20 in the kids games US charts and I see a little bit less sales but almost marginal and I tribute it to the weekdays.
So I would say the data I collect on my app is pretty much 100% consistent with what you posted, in the same category.
Now I am not sure if I answer your question, as I would say what you can expect on the different sales ranks per nature should be pretty consistent (and I would love to see comparable data for other categories. volunteers?

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I saw your app when I was tracking mine and I remember categorizing it as unique, well executed, etc. Found the success not surprising and explainable. Oh and on the overall success and sales numbers: You made it to #4 in the US Charts, do I hear a complaint??

Seriously, the one thing we all have to fight with is that those sales numbers are kind of low and even with such a success in that category it is kind of hard to achieve a positive return on investment, esp. with a 99 cent app.
Middle of the Road? I would say in that category the only professional app is the Disney app and I kudos it for the most amazing intro I have yet seen on an app, but the game I found kind of average, not really worth 4.99.
just random answers to your question hope you find it still useful and a real value return on you sharing data.
Markus