How do I display the submitted data in the same page?
You can use $form_state['rebuild'];

If $form_state['rebuild'] = TRUE; has been set then a new copy of the form is immediately built and sent to the browser. Instead of a redirect to new page.

Example:

function example_form_submit($form, &amp;$form_state)
{
  // we return the submitted value to the form
  // by storing it in $form_state['storage'] and rebuilding
  $form_state['storage']['some_value'] = $form_state['values']['some_value'];
  $form_state['rebuild'] = TRUE;
}


You can refer https://www.drupal.org/node/2171993

Another way store the "$form_state['values']" in session. 

Take @clive answer How to display an HTML table after the form submission on the same page as the form? as reference.