| 2009 | 2014 | 2018 | Between-group differences | |
---|---|---|---|---|---|
Primary and below (n, %) | Test statistic | p | |||
χ2 = 9.383** | .009 | ||||
 Q81 Yes | 208a (86.7) | 224b (93.7) | 269b (93.1) |  | |
 Q81 No | 32a (13.3) | 15b (6.3) | 20b (6.9) | ||
Secondary (n, %) | χ2 = 3.988 | .136 | |||
 Q81 Yes | 418c (86.0) | 422c (86.7) | 568c (82.8) |  | |
 Q81 No | 68c (14.0) | 65c (13.3) | 118c (17.2) | ||
Tertiary and above (n, %) | χ2 = 22.688** |  < .001 | |||
 Q81 Yes | 245d (86.0) | 254d (89.4) | 372e (76.9) |  | |
 Q81 No | 40d (14.0) | 30d (10.6) | 112e (23.1) |