It doesn't matter how many times you swipe your card, you can get a card and never use it and and still counts for your credit history. The point being you have credit available to you but you aren't using it. You have four years of not running up your credit card, that's huge.
EDIT: Huh, apparently I've been ill-informed about credit history [1]. Guess I've been a dumbo and one of today's lucky 10,000.
[1]: https://www.reddit.com/r/personalfinance/comments/188xmi/is_...
FICO is based on your credit utilization (amount owed vs credit limit), history of repayment, mix of types of accounts (this has a minimal impact), number of new accounts, number of credit inquiries (aka hard pulls, this is also minimal), and length of credit history.
You had credit available to you for four years and you manage it very, very well.
Other scoring algorithms besides FICO may weigh different things differently but FICO is currently used in most lending decisions so it's what matters for now.
If you want to see your real Experian FICO 8 credit score for free you can do so at freecreditreport.com which is a site now owned by Experian. They break down each part of your credit score and grade you on each. (A-F)