Horton the elephant was faithful 100%.  There are a lot of stories in scripture of faithful men and women of God but none is 100%.  Fortunately God is not depending on us in order for him to be faithful.  Our God always 100% faithful to what he says.  Check out week 1 in Summer of Seuss.  

For no matter how many promises God has made, they are “Yes” in Christ. And so through him the “Amen” is spoken by us to the glory of God.  2 Corinthians 1:20