Suppressing Null values
When working with pivot tables, in rows or columns combination, if a value is present in database it is been displayed otherwise it displays blank value, as it seen here for Year Ago Dollars column.
We cannot suppress this value using ifnull(measure,0)
What we can do is replace blank with hyphen.
Edit the column properties for that particular column and in conditional format
Select operator as is null
In Edit format option select Strikethrough from effects drop down list.
Blank values will be replaced by hyphen (-)