Your score is reflecting your limited credit. As the previous person stated, lenders see the score and report and determine you don't have any credit history. Lenders want a history so they can better decide if they are OK with risking losing money by lending to you.
If you want it to improve, apply for one trade line (credit card/line of credit) Pay as agreed. Never close this trade line. Creditors want to see you have financial responsibility over time.
