The AIU calculated the daily country pair flows of flights for 2020 and
fed them to the excellent 
flowmap.blue
so that questiones like the ones below (and many others you may have in mind)
can be visualised on a map.
In the following map (or see the sections below for some examples and relevant links) play with
- the filters (top left box, or click on the circles) to select the countries of interest,
- your mouse and hover over the flow arrows or country circles to get the amount of relevant flight flows counts
- the time interval selector (center bottom) and its play button; or
- the settings (bottom left gear) in order, for example, to enable clustering
Who was flying to/from Spain in the mid August week?
Answer: Britons and Germans seems to have all flown to Spain to spend their holidays! (Or maybe Spaniards went en-mass to UK and Germany…!)
Where were flying Europeans in July/August?
Answer: Britons and Germans flew en-mass to Spain (~10k flights from/to each country); while France, Italy, Greece and Turkey took only approximately half of that (~5K flights each.)
Figure 1: Flows in/out og UK and Gemrany in July/August 2020
How was the translantic traffic like this summer 2020?
Answer: extremely low, just few flights coming in / flying out of Europe. Look for example at the very thin flow from USA…
Methodology
The pairs/counts have been derived from the country location of the ICAO indicator associated with the aerodrome of departure (ADEP) and destination (ADES).
There is a very low percentage of airport pairs where one or both of ADEP/ADES are unknown. These are usually associated with IFR helicopter flights (i.e. connections to oil platforms from/to Norway) or air filled (AFIL) flight plans.
Unknown ADEP/ADES have been arbitrarily mapped to the Null Island and not filtered out in order to keep the flow counts consistent.