Zend certified PHP/Magento developer

How do I count number of unique in a row * a counter for Excel?

For this image there are only 2 genres, Fiction and Non-Fiction throughout the entire dataset, I would like to count the total number of Reviews for each Genre.

So for the first entry, Fiction has 87841 Reviews, and it has to add the 79446 from second entry and so on, until the end.

At the end, there will be Non-Fiction and Fiction, with their respective total number of reviews.

In the end I would like to create a pie chart showing the distribution of them, but how do I get both values in the first place?