What is the usage rate for users navigating form input fields via the ‘tab’ key vs. mouse clicks?

On my current project, we are debating the usage of replacing input fields (checkboxes, radio buttons, and select dropdowns) with styled choices via javascript. However, it breaks the support of navigating between form input fields via the tab key. I tried searching to see the usage rate of normal users (i.e. not developers) navigating forms via the keyboard, but couldn't find any studies done on it.

I don't like the idea of breaking basic, expected browser functionality, but I would love to see numbers and/or advice on the usage of keyboard navigation with forms.