Mark,

There was an extended time in history when sunspots virtually disappeard, called the Maunder Minimum (named after a solar astronomer who was very active in investigating historical sunspot records) which occurred from ~1645-1715. Although I'm not exactly sure what the longest time between sunspot observations was during this time, there were less than 50 sunspots observed between 1672-1699. That's less than 2 per year on average, and in fact, I have read that there were zero sunspots observed during the 1670s. For comparison, during a typical 30-year interval there can be between 40,000 and 50,000 spots reported. Maunder Minimum is a very strange time in the Sun's history that we don't fully understand.

Holly