Add 'Next 12 months' to dates viewable drop down list in customer page

I create 12 month taylored works packages with each of my customers individually. Once the works are agreed I then create invoices for the works. At this moment Ithe default view for invoices on the customer page is 'this year'. There are other options on this list like the custom option but that requires me to create this every time I view a cutomer page (most tedious). It would be extremely handy if there was a 'Next 12 months' option added to the drop down list so we can easilly see what works we are scheduled to do for each customer.