It was fully done in Excel, yes. I explained how I did it in another response, which I post below:

I followed a simple process for making the vizualization. I had all the information about the books that I read on one Excel sheet. This was: book name, author, publishing year, publisher, language, number of pages. I would update this sheet regularly as the year passed. Then, I had one sheet where all the data was aggregated. Finally, on a third sheet, I built all the graphs and summaries mostly based on the aggregated data. I then just took a screenshot of that sheet.