New legal action by the EU against eastern member states for refusing to take their share of refugees shows how the worst migration crisis since World War II still divides the continent.

Here AFP looks at the numbers that tell a deeper story. The basic facts are stark: Since 2014, more than 1.6 million people have arrived by sea while 13,500 have died on the way.

The numbers also give answers to the important human questions: Where are these people coming from, where are they going, how many have died, and how many will be allowed to stay?

- 2015 peak -

The migration crisis has no official starting point but statistics from the International Organization of Migration (IOM) offer some chronological yardsticks.

Following gradual yearly increases since 2011, 2014 marked a first turning point with 170,100 people landing on Italian shores and 43,518 on Greek coastlines, up from 42,900 and 11,447 respectively the previous year.

But it was in 2015 that the situation took on dizzying proportions. The IOM registered 1,011,712 arrivals by sea in Europe, including 853,650 on Greek shores, with the peak in arrivals hit in October, and 153,842 on Italy's coastline.

The increase was mainly a result of the worsening conflict in Syria alongside deteriorating conditions in Syrian refugee camps in Turkey, Lebanon and Jordan.

Among the arrivals in Greece in 2015, more than half -- 56.l percent -- were Syrian, while 24.3 percent were from Afghanistan and 10.3 percent were from Iraq.

Most came to Greece across the Aegean Sea from Turkey.

While the EU struggled to forge a collective response and help Greece cope with the influx, most of the migrants trekked along the so-called Balkan route toward wealthy northern European countries like Germany and Sweden.

The arrivals on the Italian coast in 2015 came on the central Mediterranean route, mainly from sub-Saharan African countries: 39,162 Eritreans, 22,237 Nigerians, 12,433 Somalis and 8,932 Sudanese.