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Please help me for correcting the composition blew. mainly find out the wrong using of grammar or somewhere not native，Many thanks in advance.

The bar chart shows the changes of sales in 3 different areas(Game software, Cds, DVD or video) in those 4 years(from 2000 to 2003).

The volume of sale of CDs kept a highest postion of sales, though this figure indicated a slow drop among those 4 years.

In contrust, a significant increase was found in the sale colume of DVD/Vido over the same period(from less than 20 $bn to 31 $bn ).

This number for Games software also suffered a moderate rise (19 $bn in 2003, 15 $bn in 2000).

CDs owns the strongest purchasing power, which palyed an absolute lead role among media productions and hold about double times than DVD/Video, three times than Games software in 2000.

CDs and DVDs, though, still less share than CDs in 2003, but manifested an impressive captitiveness