Seniors’ use of cannabis and their support for its legalization is on the upswing. According to nationwide polling data compiled by the Pew Research Center, nearly two-thirds (63 percent) of “Boomers” (those born in the United States between the years 1946 and 1964) now say that marijuana ought to be legal for adults. That percentage is up significantly from a decade ago, when fewer than one-in-three seniors endorsed its legalization. Some of this change in…