Every day for the last week more than one hundred thousand Ukrainians have fled their home country, bringing the total number of Ukrainian refugees to more than 1.2 million since Russia's invasion began.Poland steps upMore than half of that total, around 650,000 people, have fled to Poland — Ukraine's neighbor to the west. Posts on social media have been overwhelmingly positive, with reports of Polish guards handing out food to those in waiting rooms and citizens offering clothes, hot drinks, transport or even a room to those Ukrainians in need. Similar stories can be found in Moldova, Romania, Slovakia and Hungary — 4 of the other countries that have seen the most refugee arrivals.The United Nations High Commissioner for Refugees estimates that up to 4 million Ukrainians might end up fleeing the country — which would be around 10% of the country's population.Yesterday Russia agreed to open up "humanitarian corridors", to help civilians flee safely.