The number of German suspects declined by 3.4 percent to 1,407,062.  More than a million migrants have arrived in Germany in the last two years, largely from the Middle East. Concerns over security and integration initially pushed up the poll ratings of the right-wing Alternative for Germany (AfD), but support has slipped as the rate of arrivals has slowed. Chancellor Angela Merkel's party, the Christian Democratic Union, has shown strong gains in recent polls, including in Germany's most populous state of North Rhine-Westphalia. That region goes to the polls on May 14 in what is being seen as a bellwether for the general election in September.  The UDC is currently level with the Social Democrats on 34 per cent. The number of migrant criminal suspects in Germany soared by more than 50 per…