| Measurement period |
Response rate |
| February 2011 |
|
| Mail |
17.1% (60,320) |
| Web |
3.6% (13,002) |
| Phone |
0.47% (1,673) |
| May 2011 |
|
| Mail |
19.1% (71,879) |
| Web |
3.9% (14,623) |
| Phone |
0.52% (1,959) |
| July 2011 |
|
| Mail |
17.9% (67,478) |
| Web |
3.6% (13,707) |
| Phone |
0.53% (1,989) |
| November 2011 |
|
| Mail |
20.3% (98,717) |
| Web |
4.2% (20,392) |
| Phone |
0.58% (2,831) |