diff --git a/simulation/app.py b/simulation/app.py
index 0bca4c8..71eddd9 100644
--- a/simulation/app.py
+++ b/simulation/app.py
@@ -1,4 +1,4 @@
-from dataclasses import asdict, dataclass
+from dataclasses import dataclass
 
 import numpy as np
 import pandas as pd
@@ -39,22 +39,36 @@ class Server(Process):
 
 
 class CustomerGenerator(Process):
+    def __init__(self, lam=40, servers=[]):
+        self.lam = lam
+        self.servers = servers
+        super().__init__()
+
     def run(self):
         while True:
-            wait_for = float(max(0, (np.random.poisson(lam=40, size=1) / 10)[0]))
+            wait_for = float(max(0, (np.random.poisson(lam=self.lam, size=1) / 10)[0]))
             customer = Customer(arrived_at=self.simulation.clock)
             customers_unhandled.append(customer)
-            for server in servers:
+            for server in self.servers:
                 server.resume()
             yield from self.hold(wait_for)
 
 
-servers = [Server() for _ in range(2)]
-simulation = Simulation(processes=[CustomerGenerator(), *servers])
-simulation.start()
+def run_simulation(n_servers=2, lam=40):
+    servers = [Server() for _ in range(n_servers)]
+    simulation = Simulation(
+        processes=[CustomerGenerator(servers=servers, lam=lam), *servers]
+    )
+    simulation.start()
 
-df = pd.DataFrame([asdict(customer) for customer in customers_handled]).assign(
-    queue_time=lambda row: row["started_at"] - row["arrived_at"]
-)
-print(f"\nservers: {len(servers)}")
-print(df[["queue_time", "handling_time"]].mean())
+    df_customers = pd.DataFrame(
+        [customer.__dict__ for customer in customers_handled]
+    ).assign(queue_time=lambda row: row["started_at"] - row["arrived_at"])
+    df_servers = pd.DataFrame([server.__dict__ for server in servers]).set_index("id")
+    print("\n")
+    print(df_customers[["queue_time", "handling_time"]].mean())
+    print(f"\nservers: {len(servers)}")
+    print(df_servers[["utilization"]])
+
+
+run_simulation(n_servers=2, lam=30)
diff --git a/simulation/lib.py b/simulation/lib.py
index 9c92f35..2d7b626 100644
--- a/simulation/lib.py
+++ b/simulation/lib.py
@@ -17,19 +17,32 @@ class Process(BaseProcess):
     def __init__(self):
         self.id: int = 1
         self.simulation = BaseSimulation()
+        self.started_at: float = 0
         self.resume_at: float = 0
+        self.time_active: float = 0
+        self.utilization: float = 0
         self.suspended = False
         self._gen = self.run()
 
-    @property
-    def name(self):
-        return f"{self.__class__.__name__} {self.id}"
+    def start(self, simulation, id):
+        self.id = id
+        self.started_at = simulation.clock
+        self.simulation = simulation
 
     def hold(self, hold_for: float):
         hold_for_formatted = "{:.2f}".format(hold_for)
         self.simulation.log(f"holding {self.name} for {hold_for_formatted} seconds")
         self.resume_at = self.simulation.clock + hold_for
+        t_start = self.simulation.clock
         yield
+        t_end = self.simulation.clock
+        self.time_active += t_end - t_start
+        try:
+            self.utilization = self.time_active / (
+                self.simulation.clock - self.started_at
+            )
+        except Exception as e:
+            print(e)
 
     def suspend(self):
         self.suspended = True
@@ -42,6 +55,10 @@ class Process(BaseProcess):
             self.suspended = False
             next(self._gen)
 
+    @property
+    def name(self):
+        return f"{self.__class__.__name__} {self.id}"
+
 
 class Simulation(BaseSimulation):
     def __init__(self, processes: list[Process]):
@@ -56,8 +73,7 @@ class Simulation(BaseSimulation):
             for p in self.processes
             if p.__class__.__name__ == process.__class__.__name__
         ]
-        process.id = 1 + len(processes_with_same_class)
-        process.simulation = self
+        process.start(simulation=self, id=1 + len(processes_with_same_class))
         self.processes.append(process)
 
     @property