Sub-period | △Rp | △Rw | |||||
△Rp < −2 | −2 < △Rp < −1 | −1 < △Rp < 0 | 0 < △Rp | △Rw < −1 | −1 < △Rw < 0 | 0 < △Rw | |
Ⅰ (1962−1976) | 2 | 6 | 5 | 2 | 0 | 7 | 8 |
Ⅱ (1977−1984) | 0 | 0 | 4 | 4 | 0 | 3 | 5 |
Ⅲ (1985−1996) | 0 | 7 | 3 | 2 | 0 | 4 | 8 |
Ⅳ (1997−2011) | 0 | 1 | 10 | 4 | 0 | 13 | 2 |
Total | 2 | 14 | 22 | 12 | 0 | 27 | 23 |