Calculation required

Hi All
I have a spread sheet that is looking at performance by month
What I would like to do is have a calculation in one cell that looks at the tend to see if the measure is improving or not

How my sheet is set up

In row 8 from Column "E" to "Q" I have the names of months Aug 2015 to Aug 2016
In row 9 under each of the months I enter a performance figure

In Row 9 Column "S" I want a calculation that looks at the data entered so far and works out a trend placing an arrow for 3 different scenarios Performance Improving = Arrow pointing up, Or Performance staying the same = Arrow sideways or Performance declining arrow pointing down (I would use the starting data as per the cell E8)
with this calculation I need it to realise if there is blank data then it doesn't count this as Zero

Can someone please help

Thanks