Users with the Billing Information permission can look up the amount of space currently uses on the Billing Information page.
Go to Setup > Company > View Billing Information.
The Total Storage Size (MB) pertains to your data like transactions, contact information of your employees, customers, vendors, partners; sales records like estimates, opportunities, sales orders, sales invoices, purchase orders, etc.
The File Cabinet Size pertains to the files or data you store in Documents > Files > File Cabinet, example of these data are images, customized templates, attachments are business documents.
For the data growth (File Cabinet size and Total storage size(MB)) each year. This can be found on the Billing Information page, under the Component Usage section we ccan try to create a Document Search and compare it each year.