The new month has just begun, so now we can compare the last days of March with the first day of April, 2018.
March 2018 will go down in history (so far in this solar cycle 25) as having the lowest average mean for an International Sunspot Number (ISN). It will be approximately 2.5 according to the graph provided by Belgium.
Below for your comparison are the unadjusted month of March 2018 and the updated month of March 2018 according to Belgium.
In the updated version dated April 1, 2018, there are 6 days with sunspots (March 1, 2, 16, 17, 30, and 31).
This leaves another record with 25 spotless days in March: 14 days (Mar. 3-15) followed by another 10 days (March. 18-29)
The sunspot numbers total 77 for all six days, so 77/31 = 2.48, which when rounded will give a monthly mean of 2.5.