Compare DateTime - Linq and orderby

I had to create a small chart about Asp.Net Membership users. The easy way how to do this is to use the Method GetAllUsers(). Once we loaded all Membership data we ready to run over our data with 2 simple LINQ statements:

      DateTime now = DateTime.UtcNow;
      Dictionary<datetime,> day = new Dictionary<datetime,>();
      for (int i = 0; i < 7; ++i)
      {
      DateTime compareDate = new DateTime(now.Year, now.Month, now.Day);
      compareDate = compareDate.AddDays(-i);
      var d = from a in data
      where a.CreationDate.Year == compareDate.Year &amp;&amp;
      a.CreationDate.Month == compareDate.Month &amp;&amp;
      a.CreationDate.Day == compareDate.Day
      orderby a.CreationDate descending
      select a;
      day.Add(compareDate, d.Count());
      }

      Dictionary<datetime,> month = new Dictionary<datetime,>();
      for (int i = 0; i < 12; ++i)
      {
      DateTime compareDate = new DateTime(now.Year, now.Month, now.Day);
      compareDate = compareDate.AddMonths(-i);
      var d = from a in data
      where a.CreationDate.Year == compareDate.Year &amp;&amp;
      a.CreationDate.Month == compareDate.Month
      orderby a.CreationDate descending
      select a;
      month.Add(compareDate, d.Count());
      }