Statistics/ demographics help here.
Typically people return to the faith once they have married and begin raising kids. In the US, and unfortunately elsewhere, there is this unpleasant (in many ways) trend of cohabitation.
This enormously messes with the development of the next generation, children and the creation of stable families. It also pushes off the age of first marriage, looking at the group.
In 2013, we see the start of the birth dearth cohort coming in, which means that it’s easier to say there’s a large drop, since there’s fewer to begin with.
I think the 1960s generation raised their children without developing a commitment to the faith: they did the whole “I’ll let Johnny decide for himself” business, or worse, “I won’t influence Johnny’s spiritual direction” (which in practical terms means Johnny’s totally lost and losing in this area—kind of like if parents let their kids teach themselves calculus if they want to). I don’t want to crank on this much, but it’s a factor.
And of course, during this span of years, young people are enjoying a blast of nice independence and the ability to fornicate, use drink and drugs, party and socialize. To some extent, our society has Boy meeting Girl – pair bonding — in some questionable ways.
Marriage itself has lost an economic basis, as men’s wages have been stagnant and women have entered the workforce so that the boat can stay afloat. Economic gains have gone to the Elite, not Joe Sixpack. This impacts families, as well as the disappearance of stable jobs.
Cheap stuff from Walmart is pricey in reality.