The figure has almost doubled in the last two years.

By the end of 1995, that figure had more than doubled.

But it won't be long before that figure could double.

That figure more than doubled, to over 31,000, in 1995.

The figures had doubled by the time the season ended.

The figure for 1992 has more than doubled to 1,100.

The figure has more than doubled in just a year.

And that figure almost doubled again to more than 130 in the late 1960's.

This year, the figure has almost doubled, to 19 percent.

Scientific studies suggest that this figure could double every 20 years.