How to combine values of same field in a single column of a chart created with Charts?
Edit: The module now shows individual values for each company and takes the company's latest published version's vales. So, if I made another entry for Company A and it's published, the chart will only show the latest version's values. I've also edited the body and included a picture of the final result.

It looks like building a custom module answered my own question. I had to code a module with the charts API and create a custom block to show the data (it was a huge pain writing the functions and retrieving the data). 

Instead of adding all the values into one column, what I've done is take a company's values for each year, place it on the chart, and other company values stacked on the previous company values as shown here:


To anyone else now or in the future with the same problem as me, here's a code snippet that I used:

$chart = array(
 '#type' => 'chart',
 '#chart_type' => 'column',
 '#stacking' => TRUE,
);

Include the code ^above in your function that displays the block/module.

You will need to make your own functions and may be you'll need to implement some of the functions as shown in WD Tutorials for Drupal.

Also, for getting the field data, I made a function that shows all the years (in sequential order). I made several variables: holding a result of an array to store the years, counters (for an array counter, year counter, etc.), an offset for the current year, and a variable for a hard limit (having an arbitrary hard limit is bad). I made use of two while loops that checked to see if the data field (e.g. field_data_field_(insert name of field)) to check if it exists and to see that year contained any rows (indicating that having any values in the table shows that it exists).

As for the other functions, I made separate functions such as filtering duplicates, retrieving all node IDs that are Company content type, and getting each of the node's ID values.

For anyone that's stuck on Drupal's PHP syntax, I would suggest looking at PHP first and then comparing it to Drupal's PHP documentation (confused me at first).

Thanks to all that offered me help during the process. It got me thinking better.