A manufacturing process is monitored using a P-chart for the proportion of defective items in a sample of 50 items taken every hour. The process has been in control for the past 20 hours. The historical average proportion of defects is 2%. During these 20 hours, the proportions of defective items in each sample were as follows: 

[0.03, 0.02, 0.02, 0.04, 0.03, 0.02, 0.03, 0.05, 0.03, 0.04, 0.02, 0.03, 0.04, 0.03, 0.02, 0.03, 0.03, 0.04, 0.02, 0.03] 

a. Calculate the centerline (CL) and the upper control limit (UCL) for the P-chart. 

b. Using the data provided, determine if the process is currently in control. If not, which points (if any) are out of control? explain by using excel sheet.