Growth Projection

Hi Team,

I have the requirement to increase tablespace size in production taking a future row count projection.

like below table future growth projection, the number indicates an Orders per Year.

2012    2013    2014    2015    2016    2017    2018
0    0    2,505    19,589    27,192    28,308    29,468
0    0    2,824    258    0    0    0
0    0    5,329    19,847    27,192    28,308    29,468

any one suggest me how can I calculate tablespace growth based on the number of orders per year as per above figures.

Thanks
GKris