There are two types of Pick List reports you can run; 4-Week Trend, and Sorted By Station/Demo.
The 4-week trend report will first ask you to specify an end-date and demo/gender filters. As the report will compile results for a 4-Week period (with discrete columns of results for each of the weeks), you need only supply an end-date. The report will sort through data for the 28-day period (4-Weeks) prior to and including the end-date you specify.

Pick List 4-week Trend report
In addition to displaying a total count and percentage breakdown (for the entire 4-Week period), raw count weekly totals are also displayed, as well as sample counts for each of the weeks and the total period.
See also