Astronomical Data
Here, an international monthly average sunspot numbers from 1700 to 1995 dataset is provided, which considers a time quantization of 1 month. The numbers are not unique, but represent the average of many subjective observers' estimates using the over 200 year old method of estimating the sunspot numbers. Yearly numbers prior to 1749 are guesses and are given for historical reasons.
Updated: Solar Physics (NASA)