| 年份 | 調查日期 | 樣本數目 | 抽樣誤差範圍 | 回應率 | 
| 2006 | 2, 4, 7–9/8 | 1,076 | ± 3.0% | 35% | 
| 2008 | 4-5, 8-9, 12,15-17/9 | 997 | ± 3.1% | 36% | 
| 2010 | 29-30/9; 3-5, 12-13, 26, 28/10 | 1,015 | ± 3.1% | 41% | 
| 2012 | 31/10; 1-2, 5-9, 11/11 | 948 | ± 3.2% | 38% | 
| 2014 | 15-19, 23, 29-30/12/2014 – 2/1/2015 | 863 | ± 3.3% | 31% | 
| 2016 | 25, 28-30/11; 1-2, 5-9/12 | 1,124 | ± 2.9% | 37% |