How Do I Add Spawn Chances For An Enemy Per Area?

List<Enemy> ExperimentationEnemies = new List<Enemy>();
ExperimentationEnemies.Add(New .....)

List<Enemy> ExperimentationEnemies = new List<Enemy>();
ExperimentationEnemies.Add(New .....)

List<Enemy> ExperimentationEnemies = new List<Enemy>();
ExperimentationEnemies.Add(New .....)

List<Enemy> ExperimentationEnemies = new List<Enemy>();
ExperimentationEnemies.Add(New .....)

Enemies currently contain a Name, Health, Damage and Attackspeed.
I am now not sure where or how I should add Spawnchances.