This placeholder creates the sum of all users of certain values.
Placeholder SHBOARD_SUM("User attribute", "Content")%
The first attribute defines the user attribute to be summed. A list of possible user attributes can be found HERE.
Example:
SHBOARD_SUM("extra_2", "null")%
This returns the sum of all empty fields in the "extra_2" column in the user table. The return value is a number.