Paul Singer

USA TODAY

Libertarian presidential candidate Gary Johnson is generating less than 10% the weekly Facebook traffic of Democrat Hillary Clinton, but he leads her in one interesting category: youth.

USA TODAY's new Facebook Candidate Barometer shows 38% of the Facebook users interacting about Johnson last week were 34 years old or younger, while only 23% of the people chatting about Clinton were in that age group.

In general, Clinton's Facebook conversation trends older. The data provided by Facebook shows 39% of the likes, shares, comments and posts about Clinton last week came from users 55 and over, the highest total among the four major candidates. Johnson scored lowest in this category, with only 24% of the conversation about him coming from users 55+.

The conversation about Donald Trump is more evenly split: Both age groups generated 31% of the chatter about Trump on Facebook last week.

Green Party candidate Jill Stein trended young, with 35% of the conversation about her coming from the 34-and-under group and 29% coming from 55 and up.

The USA TODAY/Facebook Candidate Barometer tracks weekly data provided by Facebook on the interactions about the candidates on the social platform. It tracks volume, not sentiment: We have no idea how many of the comments are negative. But the data allows you to see where in the country each candidate is having their greatest impact on the Facebook conversation, and it shows trends in traffic over time that can be interesting. For instance, political conversation clearly dropped off in August: None of the candidates produced large total traffic numbers during the month. And Johnson's Facebook demographic has consistently been heavily dominated by younger users.

The challenge for Johnson and Stein is getting heard over the huge volume of chatter about Clinton and Trump. Facebook users generated 75 million interactions about Trump last week and 48 million about Clinton, while Johnson got only 4 million interactions and Stein just over 1 million. It's hard to win a presidential race if people aren't talking about you.

2016 USA TODAY/Facebook candidate barometer