What does 0/3, 1/3, 1/4, 1/11, etc. mean in the context of assigned reviews in a journal management system? I have submitted a paper in a mathematical journal 04 months ago. A part of the online system of this journal is showed in the following figure. 

I see that, after 01 month, status of "Assigned reviews completed" is "0/3". Next, after 02 moths it is "1/3", after 3 months it is "1/10" and now is "1/11".

What are this means? What should I do in this case? A letter to editor for a inquiry or no?

Thank you for your comments.
My intuitive guess is that it's the number of reviewers who have completed their reviews / been invited to review. The journal invited 3 reviewers in the first month. Two months later, one reviewer finished the review, but the other two either didn't accept the invitation (more likely) or didn't submit a review. The journal's policy is to have at least two reviews per paper, so they invited more reviewers, to the current count of 11.

If this guess is correct, then there's nothing to do except wait. You can also write to the publisher asking what the number means - it can cause no harm.