Merged cell to show automatic percentage increase or decrease

As per the attached image, I'm trying to create a formula that will automatically calculate either the percentage increase or decrease between two different amounts. So, in the merged cell B4 it is showing -4%, which is a 4% decrease between cells B3 and C3. However, I only used that formula because I knew it was a decrease. Is there a formula that I can paste into each of those merged cells along Row 4 that will automatically show either the percentage increase or decrease of the adjacent two cells above in Row 3? Thanks!