I think Europeans now hold more bitcoins. They have many money laundering activities that we don't know behind. Do you see that China has many bitcoin billionaires because its press is free to interview bitcoin billionaires? In the United States and some European countries, bitcoin billionaires often have to remain anonymous so they won't be sought by the government.
Besides, the most typical example is the big fluctuations of bitcoin usually taking place around the morning in Europe, especially in the US.