Display salaries from all currencies

[NicolasPA]

It seems it is not possible to display the graph for all currencies.
By default, the graph shows for USD and ignores everything else, if you select anything else then you can't see USD entries.

For example, if I look at Germany in EUR I see many entries, and if I look at Germany in USD, I see one entry, they are mutually exclusive. There should be a way to see all the Germany entries regardless of the currency selected.

A good solution would be to default the currency filter to the value "All currencies" and convert all entries to a default currency, so the graph displays every entry.

A lazy solution is to remove the currency choice in the entry form and ask everybody to enter their salaries in USD.