Why is the earning value of posts on steemit dropping?

I have noticed that the earning value of my post are dropping day by day. I guess I have noticed it because I only earn a few steem dollars per post. But a post from last month I have not received single Steem dollar or steem for my posts. Every post is showing $0.00 from last month. Sometime I have received more than 10 upvotes in my post but still it is showing$0.00.

I am Just wondering has anyone noticed this or can anyone from steemit explain whats going on? I also noticed the earning on up voted comments dropping too..