kotlon wrote:
DATE VALUE
1959-01-01 286.6
[....]
1961-01-01 314.1

This is the monthly data. How can I calculate the growth rate from 1959
to 1960?

I assume you mean "through 1960" or "to 1961".

First, to compute the monthly rate, you could use one of the following:

=(314.1 / 286.6) ^ (1 / 24) - 1

=rate(24, 0, -286.6, 314.1)

Don't forget to format the cell Percentage with 2 or more decimal
places.

There are two schools of thought on how to convert monthly rates to
annual rates. One school simply multiplies by 12. The other school
computes the compounded rate over 12 months, for example with one of
the following:

=fv(monthlyRate, 12, 0, -1) - 1

=(1 + monthlyRate) ^ 12 - 1

=(314.1 / 286.6) ^ (12 / 24) - 1

The last formula simply combines the middle formula with the first
monthly rate formula.

PS: I suspect these are CPI numbers. If they were stock prices, there
is yet another school that would multiply the monthly rate by the
SQRT(12). This is the "square root of time" rule, which you can learn
about by doing a google search. It is valid only if certain
statistical conditions are met, including that the periodic changes are
presumed to be independent and normally distributed. I have never
heard those assumptions applied to the CPI.