I have 2 columns (A:B). A is numbered 1-17. B then has % figures in some of
the rows. I want to interpolate the gaps between these figures (see example
below).

At present I do this manually using the following formula:
((a-b)/x+c)
Where a is the 1st known amount above, b is the first known amount below, c
is the value of the row below, and x is the number of steps between a and b
(e.g. row 1 to 4 is 3 steps).
Row 1 will always have a figure in it, but the rest are then random and
there is no need to interpolate after the last figure (which may be at any
point from row 1-17)

I would like to be able to do this automatically, where the known amounts
are input, and then the other figures calculate - the output would preferably
be in a new column.

Any ideas?

E.g:
Inputs Desired Result
1 13.40% 13.40%
2 10.90%
3 8.40% 8.40%
4 6.83%
5 5.27%
6 3.70% 3.70%
7 2.93%
8 2.17%
9 1.40% 1.40%
10
11
12
13
14
15
16
17