Looking for someone who knows about health statistics

No.12718094 ViewReplyOriginalReport
How does the CDC estimate the death totals for specific subsets of death totals. Like Radon deaths for example are estimated at 20,000 a year in the U.S.

Obviously they aren't tallying up 20,000 confirmed radon deaths. How do they come up with the year over year average and how do they know when to change it?