In "Biblical Perspective" Gordon Snider writes:
We must not forget that what God has done for us is just a small part of the big picture of God's activity. The history of Israel abounded with the redemptive works of God, and from then until now the list continues to grow. The very fact that God considers man at all is amazing. God not only thinks about us, but makes plans for our good. The thought of the psalmist turned to considering a proper response to what God had done. The magnitude of mercies is so great as to be impossible to arrange them in order of greatness or even to count them.
Source: Studies in the Psalms: Adult Teacher's Insights, page 35.