The chart below was derived using this link, pulling off the top ten song hits from each year. If I recognized the title & artist I counted it as familiar.
Using this list of the top 100 films of all-time (in terms of box office receipts adjusted for inflation), I separated them by decade and then charted the results. Predictably the familiarity declines less with age than had music. Pop songs are more accessible to the young than movies, at least back in my day, and movies tend to have a longer shelf-life:
But there's no question that I was heavily, incredibly involved with pop culture during the '80s. Almost 100% of the top movies and music commanded my attention. It seems impossible to argue that this is other than an entirely age-related phenomenon although I would argue that the '80s music and culture is more accessible. In the '90s came the rise of hip-hop and rap, which is arguably far less ear-friendly than the melodius pop of Michael Jackson or Madonna. (But then that's what every generation says, don't they? :-)
And during the '80s/Reagan era, at least based on the big hit movies, Hollywood was more likely to provide morally unambiguous (though often shallow) offerings like Ghostbusters & Back to the Future instead of the 1970s Rocky Horror Picture Show, Animal House, etc...Cultural products accessible to a large audience are more likely to be indulged in, although I still think it would be going too far to say I didn't leave popular culture, popular culture left me.
It would be interesting to graph the amount of time I spend reading and see to what extent my disengagement in popular culture has resulted in more time spent with books. But I don't have the stats on that...