SQL Percent Change

I am using the code below to get database size. The ending temp table keeps a history of each run in the same table... For example:

RecordID  Name  Date            Value
1              MyCol  07/15/2009  50
2              MyCol  07/16/2009  55
3              MyCol  07/17/2009  40
4              MyCol  07/18/2009  60

Want I want to do, is write a query that takes the two most recent entries and calculates the change percentage between the two. Using the example above, this is what I would want the end result to look like:

RecordID  Name  Date            Value  Change
4              MyCol  07/18/2009  60       50

IF OBJECT_ID('[tempdb].[dbo].[#DatabaseFiles]') IS NULL
  BEGIN
      SELECT TOP 0 * INTO [#DatabaseFiles]
      FROM sys.database_files            
 
      ALTER TABLE #DatabaseFiles
      ADD CreationDate DATETIME DEFAULT(GETDATE())
  END        
 
IF OBJECT_ID('[tempdb].[dbo].[#DatabaseFilesHistory]') IS NULL
	BEGIN
		CREATE TABLE [#DatabaseFilesHistory]
		(
			  [database_name]		[sysname]		NOT NULL
			, [database_size]		[decimal]		NOT NULL
			, [database_state]		[nvarchar](60)	    NULL
			, [database_max_size]	[decimal]		NOT NULL
			, [database_growth]		[decimal]		NOT NULL
			, [create_date]			[smalldatetime]	NOT NULL
		)
	END
 
 TRUNCATE TABLE #DatabaseFiles        
 
 EXECUTE sp_msforeachdb 'INSERT INTO #DatabaseFiles SELECT *, GETDATE() FROM [?].sys.database_files' 
 
INSERT 
  INTO	[dbo].[#DatabaseFilesHistory]
		(
			  [database_name]	
			, [database_size]	
			, [database_state]	
			, [database_max_size]
			, [database_growth]	
			, [create_date]					
		)
SELECT	  name 
		, CAST(((size * 8.00)/1024.00) AS DECIMAL(18,2))
		, state_desc
		, CAST(((max_size * 8.00)/1024.00) AS DECIMAL(18,2))
		, CAST(((growth * 8.00)/1024.00) AS DECIMAL(18,2))
		, CreationDate
  FROM	[dbo].[#DatabaseFiles]
  
SELECT	*
  FROM	[dbo].[#DatabaseFilesHistory]
 ORDER
	BY	database_name ASC, create_date DESC

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