Help with set analysis on NSS data

[#1]

Hi,

I have a chart expression which calculates the percentage agreeing to a question.  When users drill down to their own department, I want to also have the average for all departments.  So for any particular survey question or survey section I want to be able to have the following:

                    % Agree           All Departments % Agree     

Year 1        **%                         **%

Year 2         **%                        **%
Year 3         **%                        **%

I've tried doing this using set analysis but I just get the overall % Agree, not the overall % Agree for each year period.

Time period field: NSSYEAR

% expression: sum(AGREEN*Data)/sum(ALLN*Data)

Dimension: NSSQ (NSS question or section)

({1} AGGR(sum({1}AGREEN*Data)/sum({1} ALLN*Data),NSSYEAR))

I realise the above is a bit garbled but any help would be gratefully received.