Negative interest rates are common in developed market economy. This is real market, so negative interest rates are also everyday in a whole worldwide markets.
I don't think this is very common...
I haven't heard of examples except Switzerland and Sweden, do you have more examples ?
I heard that Japan got the same 'problem'.
If there was such a thing in my country I would make sure to turn all my money into either stocks or bitcoin.
I will not pay interest to own money.