I am working on a planning project that involves projecting populations. I am
given populations for each decade (2010,2020,2030,2040) and after determining
that the growth is projected to be linear, I would like to project the
population for each year in each decade. Can a function in Excel be entered
that can determine the number of years between 2000 and 2010? I am asking
this becuase I may need to use a range of odd years (i.e. 2011-2036). The
fomula would be as such:

=(Population in 2020-Population in 2010)/(number of years in range of
2010-2020)

it is easy to count the number of years (11 including 2010) but for odd
ranges I do not want to have to sit and count. Yes, It will be easy to create
a column for "year" and do a "count" function, but I want to be as efficient
as possible.

Thanks for the continued help!