The numbers are expected to double again by the year 2015.

The number is expected to double by the end of next year.

China wants to double the size of its economy by 2020.

At this rate, the city's population is expected to double by year 2080.

This number is expected to double by the year 2030.

The Americans doubled in number every 25 years by natural increase.

This is expected to have doubled by the end of 1990.

The school opened in 1851 with about 30 students; the population doubled by 1853.

Air traffic is expected to double by the turn of the century.

The company doubled its number of employees in two years to 50 by 2007.