My minimum has been around $3 and my maximum has been just over $20. This month I am headed for an all time high of $24+. I write mostly short fiction, so I'll never see high levels of income here on HP, although the vertical sites are improving my page views dramatically. I looked over your hubs and will make some suggestions since you asked for the help.
I would suggest writing new titles for everything and having the title give a clear indication of the content of the hub. As I scanned your titles, I was puzzled by many titles. Readers aren't going to investigate. It has to be crystal clear. Here is an example from your own list of hubs.
Synopsis: We have heard many stories of wild animals crossing the jungle and entering the cities. Have we ever thought as to why they cross over?
The synopsis is actually very interesting, and it is information I would be interested in knowing.
Title: Why was the snake killed? Is it because?
The title is confusing. I would not click through to the hub if I found this on Google.
I would suggest getting help from someone who speaks English as their first language. If you make this small adjustment to each of your hubs, you should see more page views and your earnings will begin to rise.
I hope this suggestion helps and you see higher levels of income in the future.