Calculate Year on Year variance in SQL Server

--Create Table E 
--(y int,sale decimal(18,2),x float)

--insert into E(y,sale,x) values(2012,200000,0)
Declare @y int, @sale decimal,@salePre decimal
Set @sale=210000
set @y=2014
select @salePre = sale from E where y=@y-1

insert into E(y,sale,x)
select @y as year,@sale as sale,((@sale-@salePre)/@salePre)*100 as Variance
select * from E

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