The graphics represent solar cycles 21-23. The red line is the monthly smoothed sunspot number while the blue line is the actual monthly sunspot number. Cycle 21 started in June 1976 with a smoothed sunspot number of 12.2. Cycle 22 started in September 1986 at 12.3. Cycle 23 started in May 1996 with the monthly SSN at 8.0 and peaked in April 2000 at 120.8. The last smoothed monthly sunspot number is for March 2007 at 10.8.
The current solar minimum will likely be in August-November 2007 with cycle 24 peaking in 2011 or 2012.
This page is maintained by Jan Alvestad once a month. Provided that credit is given, the graphics can be freely copied. Data source: Sunspot Index Data Center in Brussels.