I was given a task to find out why a website suddenly had a drop in their organic ranking. A company specializing in SEO sent my client an email about the organic ranking drop. They had a chart showing a big drop from December 2017 to January 2018. The client has no previous records of their organic ranking or of the SEO used and updated on the website. How did this company find a chart to track my clients websites organic ranking? I am trying to use google webmaster tools and semrush to look into this since I am quite new to SEO implementation.