Increase the minimum sentence for murder to 20 years

My little brother was killed by a friend of ours, but only received a sentence of 16 years, one year more than the normal minimum. We believe a sentence of 15 years is a joke, and that the sentence my brother's murderer received does not reflect the loss of my little brothers life! We know one day the murderer will walk free, but my little brother will never see another sunrise or feel the warmth of the sun on his face or hear the rain fall. We are going to suffer for the rest of our lives.