plural or singular for trend

Hi there,

I am explaining a graph in a report and it shows the annual changes in foeign direct investment in a certain country by year.
For the title I want to write "Scale(s) and Trend(s) of FDI in xx country". Should I make the scale and trend plural? The graph is about one country and the graph shows figurs by year (e.g. 10 years).

Thank you for your help