Charts are like a matrix so the category and series groups in charts are just that: Groups. Therefore you can use them as a scope for aggregations.

Change your chart back to a normal column chart and put the Criteria in the Category Group and the Year in the Series Group.

So each bar is now the Count grouped by the Year and Criteria.

So get the yearly total you'd want the count grouped by year only.

To get the group name for years first click on the series group then press F4. In the properties window expand Group and make a note of the name (it will be something like Chart1_SeriesGroup1), this is the group name for your series group, or years.

You can then use this in an expression for your data labels. Divide the value at that datapoint by the aggregate scoped scoped over just the Years.

E.g.

=Sum(Fields!Count.Value) / Sum(Fields!Count.Value,"Chart1_SeriesGroup1")

This will divide the datapoint (i.e. the count of the Criteria and Year by the Year total). You can then format the label as a percentage.