In the following, replace MyField with the real name of your field.
In the report (or group) footer put a text box in which you can type
=Sum([MyField]=1 OR [MyField]=2 OR [MyField]=0) * -1
Alternatively, you may want to add 3 fields to your query
eg
Has1: IIF([MyField]=1,1,0)
Has2: IIF([MyField]=2,1,0)
Has0: IIF([MyField]=0,1,0)
Now you can sum up the indivual responses in a text box with eg
=Sum(Has1)
or sum up the whole group with
=Sum(Has1) + Sum(Has2) + Sum(Has0)
Evi