Averages In Matrix

I am new to Reporting Services on SQL Server 2005 and I need help. I have a report that I have create below using matrices.






















Qtr 1

1
2
3
4
5
6
7
8
9
10
11
12
13
Total

2004
80
60
70
95
70
85
60
90
110
55
90
90
50
1005

2005
5

5
10
20
5

5
5
5
5

10
75

The columns represent each week in a quarter and the row represents the year the week is in and the details is the number of new accounts created during that particular week of the year. I have couple of questions.

How do I get and average for the number of account created per week per quarter?

How do I create a percentage of the change of accounts per week per year?


















Qtr 1

1
2
3
4
5
6
7
8
9
10
11
12
13
Total
AVG

2004
80
60
70
95
70
85
60
90
110
55
90
90
50
1005
77.31

2005
5
0
5
10
20
5
0
5
5
5
5
0
10
75
5.77


-93.8%
-100.0%
-92.9%
-89.5%

-71.4%
-94.1%
-100.0%
-94.4%
-95.5%
-90.9%
-94.4%
-100.0%
-80.0%



Thanks in Advance.