Begin with add services and interfaces

Back/skydiveLogs-api.DomainBusiness/Interfaces/IStatsByYearService.cs

@@ -0,0 +1,13 @@
+using skydiveLogs_api.Domain;
+using System.Collections.Generic;
+
+namespace skydiveLogs_api.DomainBusiness.Interfaces
+{
+    public interface IStatsByYearService
+    {
+        #region Public Methods
+        IEnumerable<Statistic> GetStats();
+
+        #endregion Public Methods
+    }
+}