How to show a data trend without a chart

Hello all, first post so please be gentle!

I have a list of 250+ part numbers with their corresponding sales per month for the last five years. I want to show for each part number which way the sales are trending over the years by displaying a symbol in one cell. I've found ways to display the symbol if this months was more than last, but not for multiple months - can this be done?

If possible, it would be even better if in addition, an average % growth/decline of the trend could be displayed in one cell too.

Any help would be appreciated - thanks!

Here's an example of what i want to do. The symbol isn't important although the coloured arrow is good.

The percentage increase is probably more important.

Thanks. That enables me to show whether last month is less/more than this month, is there a way to show what the % change in sales is, derived from a trend-line of all the sales?

So if for example the sales increased by 10% one month and decreased 5% the next, then +10% then -5% for all the months, the trend is up, the % is up but can this be displayed in just a couple of cells?

Ideally:-

an arrow in one column to describe the trend for all the sales over a year
and
a % value in another column to describe the % change of that trend.

to shg, thanks very much for that input, answers my question absolutely perfectly!