The solar minimum periods between Cycles18-19 thru Cycles 22-23 were only about 2 years long. But the minimum between Cycles 23-24 (the thick green line) was almost 5 years. And the current solar minimum (the thick red line) looks like itís tracking another long solar minimum. The April 2020 data shows that the smoothed sunspot number decreased a bit more.
For the record, NOAA/NASA predicts that solar minimum will be in April 2020 plus or minus 6 months.