Adding Recession

Hey everyone,

I am trying to make data where I can graph vehicle sales along with recession periods. In the attached excel I have US GDP by which 2 consecutive quarters is by definition a recession. On the left in column F and G I have vehicle sales. The problem is vehicle sales is monthly, and GDP is quarterly. I want to be able to plot with the vehicle sales recession periods, and then put it into the graph. If someone can help me place a 1 or -1 next to the vehicle sale date. -1 when that period is a recession and 1 when it isn't.

Hope that was clear, and thanks!