extracting data from stock exchange site

http://www.kse.com.pk/kse4/phps/tstop30reg.php
>
> we want to extract the data for all companies from the above mention
> stock exchange website.As the values for different companies changes
> dynamically in all fields,so we want to save(extract)the values as
> they change.
>
> we want to maintain a database of the extracted data.
>
> we want to develope a system that can maintain a dataware house
> using tha data of any stock exchange website as one mentioned above
> and after that can represent the data in the form of graph and can
> also perform prediction for different companies data.we want to use
> screen scraper for data extraction in our system,kindly suggest how
> it is suitable for us to invoke screen scraper.