phase 2

Assets/Engine/Runtime/Measurements/Session.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
+using System.Linq;
 using EscapeRoomEngine.Engine.Runtime.Utilities;
 using JetBrains.Annotations;
 using MongoDB.Bson;
@@ -13,8 +14,11 @@ namespace EscapeRoomEngine.Engine.Runtime.Measurements
         [PrimaryKey]
         public ObjectId ID { get; set; }
         public float Time { get; set; }
+        public IList<float> Percentiles { get; }
         public IList<Puzzle> PuzzlesSolved { get; }
 
+        public float MeanPercentile => Percentiles.Count == 0 ? .5f : Probability.Mean(Percentiles.ToArray());
+
         [UsedImplicitly]
         public Session()
         {