| 1970 -72 | 1973 -76 | 1977 -80 | 1981 -84 | 1985 -88 | 1989 -92 | 1993 -96 | 1997 -2000 | 2001 -04 | 2005 -08 | 2009 -12 | ||
| βt ≥ 1 | 35 | 48 | 48 | 48 | 48 | 21 | 0 | 40 | 48 | 44 | 48 | |
| significant at 5% | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
| βt < 1 | 0 | 0 | 0 | 0 | 0 | 27 | 48 | 8 | 0 | 4 | 0 | |
| significant at 5% | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
| βt ≥ 1 | 35 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | |
| significant at 5% | 9 | 48 | 47 | 40 | 48 | 48 | 48 | 48 | 48 | 48 | 48 | |
| βt < 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
| significant at 5% | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |