Data source:
Long-Term Sunspot Numbers
Data source:WDC-SILSO, Royal Observatory of Belgium, Brussels Note from SILSO: Since July 1st 2015, the original Sunspot number data are replaced by a new entirely revised data series. On this occasion, the data are presented in a new array of files, containing additional values that were not present in the original series. For proper tracking of those changes, the present version is numbered 2.0. (Data are through December 2024, Last modified: 2025/01/01)