I've got a list of data representing monthly revenue. Overall, I can see the
trend is moving up. But I'd like to be able to say precisely how much
revenue has increased over time. I looked at the GROWTH function, but thats
for predicting a trend, not calculating a historical rate.

When I plot the data on a column chart and use a Linear Regression Trendline
I get a positive number R2 = 0.0404 (I'm sure tha's good but I can't explain
why). The values are 6560, 5970, 6290, 6640, 5950, 5900, 5880, 5850, 7370,
6300, 6700, 6310.

How do I intepret r-squared? Can I use r-squared to calculate an annual
growth? Or should I skip that and use some other means of calculating
growth?