<span>Period of a wave is the time needed for one complete cycle of vibration to pass a given point. Frequency and period have a reciprocal relationship. Frequency can be similarly thought of as speed of a wave.</span>
The record level in immigration to Germany for last 2 year have challenge the country populations estimate. But reason of Germany is favorable profile is rapidly change is not to post pone in political painful policies decision about the retirement and the pension.
At the beginning of century, Germany was forecast to lose over 1 million inhabitants by 2050 so due to declining immigration and lower average birth rate. so that now population estimates are very bright. According to the government's latest estimates, Germany population exceed 80 million by the 2060, and labor supply shortages may not be as severe in past.
Population estimates have to be substantially corrected, as the number of immigrants in Germany has fluctuated wildly and unexpectedly against immigrants from Germany, which are relatively stable.
During high-immigration time such as the early 1990 the collapse of the Soviet Union or Balkan war in mid 1990 so population estimates are very promising because it is believed to be pure migration.
