Market Research - US Tax Professional Industry

We are making automation software for the US tax service professional industry. We are looking for market research data for the business plan. The research should cover the current US tax industry such as how many tax services (CPA) firms, tax law firms; how many tax professionals; what software they are currently using; industry revenue, etc. please include your previous market research cases (relevant or irrelevant). The deliverable should be a slide deck including data references.