Why is the federal government so interested in my small business all of a sudden?

The U.S. Census Bureau sent me several pages of questions to fill out about every detail of my business and its finances, telling me they were gathering data for future use and that I was required by law to fill it out. I've owned this business for a long time and have never received any inquiries like this before. Is this unusual, or does the government routinely ask highly personal questions of small business owners?