The International Telecommunications Union recently published many information for free, which had been locked for years behind an often impressive cash house or had been available just for a few blessed.
Among these information is a bonanza of 2,5+ million of normalized field strength data from the years 1969 to 1993. This time covers two solar cycles and by far doesn’t provide insights of only historical interest: You e.g. may visualize some circuits to see the influence of day, time and solar activity at a glance. And you may use this data to analyze some dependence between field strength and solar/geomagnetic activity.
As these data so far hasn’t attracted any interest of ham radio magazines, we are just at the beginning to make use of it. Join in!