Data Interview Qs - Percent of months logged in

You're given the following table showing user logins to your system:

Table: login_info

Using the table above, write a SQL query that returns percent of months each user has logged in to your system. Your numerator will be the number of months a user has logged in, and your denominator will be the total number of months that a user has been registered in your system (here you can use the user's last login - first login as a proxy for this metric).

Here's an example of what your output table should look like:

You can view/query the data in an interactive SQL fiddle here.