Add an action to retrieve un simple summary with

the total of jumps and the last jump

Back/skydiveLogs-api.Business/Interface/IStatsService.cs

@@ -22,5 +22,7 @@ namespace skydiveLogs_api.Business.Interface
         IEnumerable<Statistic> GetStatsForLastMonthByDz();
 
         IEnumerable<Statistic> GetStatsForLastMonthByJumpType();
+
+        SimpleSummary GetSimpleSummary();
     }
 }