The score depicts a statistical forecast. For example, it states how probable it is that a person will meet their payment obligations in the future. A score of 100% would mean that a payment default is absolutely and generally ruled out.
But it’s like this. Even if you have paid everything in your life contractually so far, situations could theoretically occur in the future that would prevent you from meeting your payment obligations. For example, due to an illness, the loss of your job or also death. Consequently, a score of 100% can never be reached, because there cannot be a complete guarantee of payment.