In a statistical study at a hopsital emergency room, body temperatures of patients are taken using an oral thermometer when they enter the hospital. A sample of temperatures of 16 patients is listed below. The temperatures are recorded in degress Fahrenheit. If these 16 temperatures are a subset of all the patients entering the hospital emergency room on March 15, 2020, found by recording the temperature of every 5th patient who enters, what type of sampling method was used. 98.2, 98.1, 98.6, 99.3, 98.9, 98.7, 99.5, 102.2, 100.7, 100.3, 97.9, 98.9, 101.1, 98.0, 98.3, 100.4