Google Trends Graph and KW Planner Monthly Searches?

[JoshBowers2012]

I'm trying to show people the trends of certain keywords/topics over a period of years

Keyword Planner gives some actual numbers but only for 12 months.

Trends will show "Numbers represent search interest relative to the highest point on the chart. If at most 10% of searches for the given region and time frame were for "pizza," we'd consider this 100. This doesn't convey absolute search volume."

Which I don't really understand, other than if the graph goes up it means more interest but has to do with the amount of people searching, location, etc which can get tricky?

I'd like to put together a short report explaining certain topics and how interest in them has increased over the last 5+ years. I'm hoping someone else here has had some experience with this and has some advice or links with more information?