Explore Query - Solved ticket within 1 week

Hi, I'm looking to create a metric for solved ticket performance, I want to be able to display the percentage of tickets which were solved within 1 week, in any given week, e.g. in a given week, if I had 10 tickets created and solved 9, therefore leaving 1 still unsolved, I want to report 90% success rate.

I'm struggling to come up with a formula to produce this, any ideas please?

Once I have it, I want to create a table and a graph which shows the performance for the previous 6 weeks.