Suggestion

Ok, I took a look and you can actually go back as far as you like. The date picker is just not very intuitive about how to keep going back in time with the years. The developer of that plug in should put an "(Older)" selection at the top of the years to automatically scroll back the years.

What you do is pick the oldest year in the date picker. The click the year drop down again. What you will see is that every time you select the drop down it adds older dates. I think it is probably just simpler to type in the date, frankly for those more "senior TM".