DecimalCollection

This is my DecimalCollection that i use in my Technical Indicators Library. I would like your comments on this source.

public class DecimalCollection : CollectionBase, IEnumerable<Decimal>, IEnumerator
{
   private Int32 _CurrentIndex = 0;

   public virtual void AddRange(Decimal[] items)
   {
      //Rule CA1062
      if (items == null) throw new ArgumentNullException("items");

      foreach (Decimal item in items)
      {
         List.Add(item);
      }
   }

   public virtual void AddRange(DecimalCollection items)
   {
      foreach (Decimal item in items)
      {
         List.Add(item);
      }
   }

   public virtual void Add(Decimal value)
   {
      List.Add(value);
   }

   public virtual Boolean Contains(Decimal value)
   {
      return List.Contains(value);
   }

   public virtual Int32 IndexOf(Decimal value)
   {
      return List.IndexOf(value);
   }

   public virtual void Insert(Int32 index, Decimal value)
   {
      List.Insert(index, value);
   }

   public virtual Decimal this[Int32 index]
   {
      get { return (Decimal) List[index]; }
      set { List[index] = value; }
   }

   public virtual void Remove(Decimal value)
   {
      List.Remove(value);
   }

   private Decimal Sum()
   {
      Decimal sum = 0m;
      for (Int32 i = 0; i < Count; i++)
         sum += this[i];
      return sum;
   }

   public virtual Decimal Average()
   {
      if (Count > 0)
         return Sum()/Count;
      else
         return 0m;
   }


   #region IEnumerable<Double> Members

   IEnumerator<Decimal> IEnumerable<Decimal>.GetEnumerator()
   {
      foreach (Decimal item in InnerList)
      {
         yield return item;
      }
   }

   #endregion

   #region IEnumerable Members

   IEnumerator IEnumerable.GetEnumerator()
   {
      return this;
   }

   #endregion

   #region IEnumerator Members

   public object Current
   {
      get { return this[_CurrentIndex]; }
   }

   public Boolean MoveNext()
   {
      if (_CurrentIndex < Count)
      {
         _CurrentIndex++;
         return true;
      }
      else
         return false;
   }

   public void Reset()
   {
      _CurrentIndex = 0;
   }

   #endregion
}