To Get the Ruleset Count by Activity and ImportToExcel in Application. This solution is useful for :

1. Check the Rule sync with other environments and
2. To compare the rules in one environment with another environment in Excel.

I have implemented this by using modifying steps in "OpenUIDefaults” Activity in “Rule-RuleSet-Name” class.  

1. Loop the RuleSetVersionsList.pxResults and use Page-Remove method and remove some of the pages from it (mentioned in the doc). Import to Excel should contain only Plain Pagelist, so removing embedded pages from list. 
2. Call @baseclass.pxConvertResultsToCSV by passing the neccessary parameters.

To understand complete steps, please check my document attached below.

Happy Learning....