Calculate slope of a data set

[kux]

Hello everyone,
I hope someone is out here who can help me with a simple calculation...
I have a sales data base in access with monthly sales history by
product. to make future predictions I need the slope (representing
growth) of monthly sales.
the data is setup in a crosstab with the months in different collums,
say column 1 to 12 for last year. I want to calculate the slope for
every row (on the same query or another if needed)

Does anyone have an idea how to calculate the slope of the trendline
for those values? In excel I can just use =slope(known y's, known x's).
the slope i need is from the trendline in common statistics (I believe
it is calcuated by minimizing the sum of the squared deviation - OLS)

I cannot use an ordinary excel export (too many lines).

Anyone an idea how to work around that?

Help is much appreciated,

Thanks
Kai