Most likely this is due to a rapidly changing age distribution in Sweden. It seems, probably mainly due to immigration, that the population of ages 20-60 have

Most likely this is due to a rapidly changing age distribution in Sweden. It seems, probably mainly due to immigration, that the population of ages 20-60 have increased significantly since 2010, while the population of ages 60+ have increased less. http://www.statistikdatabasen.scb.se/pxweb/en/ssd/START__BE__BE0101__BE0101A/BefolkningR1860/table/tableViewLayout1/ http://www.statistikdatabasen.scb.se/pxweb/en/ssd/START__BE_... This won't skew the average age very much, but will definitely reduce deaths per capita. If mortality was calculated as a function of age distribution september would likely be average and april would have had a high excess mortality.