Number of solar cycle

Minimum Rz < 20

Increasing 20 ≤ RZ ≤ 100

Maximum Rz > 100

Decreasing 100 ≥ RZ ≥ 20

20

1971-1975

21

1976

1977-1978

1979-1982

1983-1985

22

1986

1987-1988

1989-1991

1992-1995

23

1996