What % of users are still playing the game daily?

I am going to share a question that I was asked in a data science interview. I failed the interview as I couldn't answer the question and still now I don't have any idea how to solve it.

Below a data table is given. It's about number of users of a mobile game. Users Assigned = Newly added users on a day. Active users = Total users active on a day.

The question is- What % of users are still playing the game daily? Options are

1. Almost 5%
2. Almost 10% to 15%. And I was ask to show the step by step processes.

It was my first-ever interview in life, so I was nervous and couldn't solve within given time. I hope someone will answer me here and will explain it clearly.

On day 0 you have 4051 users, all of which are active.
On day 1 you have 4095 added users meaning 4051+4095, of which 5522 are active.

Given that registration seems to indicate activity, we have to exclude those that registered today, meaning Day 1 active users = (5522-4095) / (4051+4095) = 0.1751780015 => 18%

Continue this until day 6 when you have 6820 active with a total playerbase of 4051+4095+3868+3921+4010+4070+4001

Day 6 = (6820-4001) / (4051+4095+3868+3921+4010+4070+4001) = 0.1006210737 =>10%