Scatter/ Bubble chart

Hi, 

We are working on a visual as displayed below. There are two lines one 45 degree line and other under it. The bubbles would always remain in the red or green region. They wont go in the white region at all. Looking for solutions on how to display both the lines. 

1. One line should always remain 45 degrees dividing the graph into to two. Other 0.75 away from the 45 degree line. 

2. If the first scenerio is not acheivable. Can I please have a constant line with 45 degree dividing the graph into two with same values on x and y axis. 

Thank you in advance. 

Thanks and Regards

Puneeth.