換題日 ---間隔天數

01/03/2014 --- 26

01/31/2014 --- 28

03/03/2014 --- 31

03/28/2014 --- 25

04/25/2014 --- 28

05/27/2014 --- 32

06/27/2014 --- 31

07/30/2014 --- 33

08/29/2014 --- 30

平均天數 --- 29.3