換題日 ---間隔天數

01/06/2010 --- 30

02/02/2010 --- 27

02/26/2010 --- 24

03/31/2010 --- 33

04/26/2010 --- 26

05/25/2010 --- 29

06/28/2010 --- 34

07/29/2010 --- 31

08/21/2010 --- 23

09/16/2010 --- 26

10/22/2010 --- 36

11/25/2010 --- 34

12/24/2010 --- 29

平均天數 --- 31.83