OK, but start here: https://www.cdc.gov/flu/about/burden/how-cdc-estimates.htm
Only “hard number” for common flu fatalities reported by doctors/hospitals is pediatric deaths, all others are CDC estimates.
“While flu deaths in children are reported to CDC, flu deaths in adults are not nationally notifiable.”
https://www.cdc.gov/flu/about/season/flu-season-2017-2018.htm
There are hard numbers for deaths. You can download the raw data that is used in the chart on the site you reference. That gives weekly death totals which can be summed easily in excel.
As another freeper says, reporting flu deaths is not mandatory. IDK but if not should it be mandatory if there is such an economic and morbidity mortality involved? Shouldn’t we have the data to drive decisions? Every patient has a cause of death, death certificate. It would be a clerical issue & could be automated.