A migrant child plays with a ball near the town of Polikastro, Greece February 23, 2016. REUTERS/Marko Djurica

BERLIN (Reuters) - The German government expects a total influx of 3.6 million refugees by 2020, with an average of half a million people arriving each year, German media reported on Thursday, in a country that took in a record 1.1 million migrants last year.

The calculations are based on internal estimates by the Economy Ministry in coordination with other ministries, German newspaper Sueddeutsche Zeitung said.

In order to project economic development, the Economy Ministry created “an internal, purely technical estimate on migration in coordination with other government departments”.

There is no official government estimate on how many refugees Europe’s biggest economy expects over the next years, as numbers are highly volatile.

But the unprecedented arrival of 1.1 million asylum seekers last year, included in the 3.6 million forecast, stretched public resources thin and put strains on German Chancellor Angela Merkel’s government.

Merkel, whose open-door refugee policy has put her under much pressure, in recent months vowed to significantly reduce the number of people arriving this year.

On Wednesday, German federal police said that they had only registered 103 migrants arriving on Tuesday, suggesting a sharp drop as a result of tighter controls along the Balkan route.

At the start of the prior week, over 2,000 were arriving on a daily basis. Last autumn the daily arrivals sometimes totaled over 10,000.