Below are the rates and total number of overdoses and emergency department visits for suspected overdose by race, ethnicity, gender, and age. The Rates are based on a population of 100,000 people. Think of rates as a type of fraction where the denominator is 100,000 and the “rate” is the nominator. This makes it easier to compare rates across different sized cities and towns and gives a more accurate idea of the overdoes effects in different demographics such as race, ethnicity, gender, and age .Raw numbers are exhibited on the MODA Dashboard by hovering over the rates. You can hover over each bar here for more detail. More about rates can be found in a PDF here: Contra Costa Health Services.