So, it would be:

1st Year: $150 - $52.50/month

2nd Year: $125 - $50.42/month

3rd Year: $100 - $48.33/month

Each Additional Year: $75 - $46.25/month

OR

We could do:

Each Additional Year: $50 - $44.16/month

The $50 drop from the 3rd year to each additional year can be a bonus.