"International migration is now the dominant factor determining the size, rate of change, and composition of most European countries. Migration is driving quite rapid population growth in some north-western countries, slowing or arresting decline in the South, accelerating decline in the East. Migration is difficult to analyse: the process is complex, the data poor, and the theory unsatisfactory. Its many factors include unpredictable policy change. But some conclusions can be reached. While immigration usually reduces the average age of the recipient populations, it cannot ‘solve' population ageing except through very high and exponentially increasing inflows. Already it is changing the face of European countries. According to available projections, the proportion of the population of foreign origin in some European countries will increase from 5–15 per cent of the total today, to 15–30 per cent by mid-century. Such projections depend primarily on the assumptions about the level of international migration."

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