There is the problem of huge population differences between the countries, so I wasn’t able to just use the absolut numbers. So I created to graphs. Once it show the migrant-population relative to the host country and once relative to their origin country.
ggplot(mig1,aes(y=Host,x=Origin,fill=sharehostpop))+ geom_raster()+ theme_gray()+ coord_equal()+ scale_fill_distiller(palette="YlOrRd", direction = 1,na.value=NA,trans='log1p')+ theme( axis.text.x=element_text(angle = 45, hjust=.1), legend.position = "bottom")+ scale_x_discrete(position="top")+ scale_y_discrete(limits=names(table(droplevels(mig1$Host)))[length(names(table(droplevels(mig1$Host)))):1])+ labs(y="Host-Country",x="Origin-Country",fill="Share of Population in Host-Country (%)", title="Biggest groups of European immigrants in Europe (2017)",caption="Note: Missing countries had no Data avaible or were so small, that they distored the scale. Source: Eurostat")