It answerred the previous question:
"After paying for so many installments (1~3yrs), why I still own so much?"
This graph show the interest has calculated base on the reducing method. Thus, an initiate paid installment has huge amount going into interest portion and only small portion into the principal.
Hints: To clear your mortgage toward the end of the tenure (e.g. last 3 years) is not a wise decision.