Highlight duplicates different colors based on how many times the duplicate appears

I have a column with dates in it, the A column.

I would like to create a script that will highlight all dates duplicated in the row, but shade them a different color based on how many times they appear.

For example if a date is not duplicated, it would have "no fill"

If a date is duplicated once, it would have interior color RGB(0, 255, 0) for all of it's duplicates

If a date appears three times, it would have interior color RGB(0, 200, 0) for all of it's duplicates

If a date appears four times it would have interior color RGB(0, 180, 0) for all of it's duplicates

If a date appears five times or more times it would have interior color RGB(0, 150, 0) for all of it's duplicates

(I'm not actually using those colors, but just inserted them for the example, I will change them later. Basically I need four different tiers of colors depending on how frequently a date is duplicated)

Thanks!