Add case number per 1000 people map layer

[yls00]

We need to add a map layer which is color by the total confirmed cases' number of the region divided by the population of the region.

[yls00]

Here is a consideration for color scheme when we look at cases per 1000. From California “The state has now been divided into 4 risk categories- widespread, substantial, moderate, and minimal. Currently, San Diego is at the substantial risk level and surrounded by areas that are in the widespread risk level. The widespread risk level is defined as more than 7 daily new cases (per 100,000 people, 7 day average, 7 day lag) and a positive test rate of higher than 8%. The second level is substantial risk is defined as 4-7 daily new cases per 100K and a positive test rate of 5-8% positive rate. The third level is moderate and is defined as 1-3.9 new cases per 100K and a positive test rate of 2-4.9%. Lastly, minimal risk is defined as less than 1 new case per 100K and a positive test rate of less than 2%.
-- Eliah