Select the *most recent* most extreme measure on dashboards
Select the *most recent* most extreme measure on dashboards

Fixes #965

annapowellsmith/openpresc,ebmdatalab/openprescribing,ebmdatalab/openprescribing,ebmdatalab/openprescribing,annapowellsmith/openpresc,annapowellsmith/openpresc,annapowellsmith/openpresc,ebmdatalab/openprescribing