By now, you probably have seen footage of frustrated journalists calling after White House press secretary Sean Spicer as he exited the White House briefing room on Tuesday. You likely don't know the whole story.

The first part is obvious: Reporters were annoyed that Spicer spoke for a grand total of 53 seconds and did not answer questions. All he did was introduce Homeland Security Secretary John F. Kelly and Office of Management and Budget Director Mick Mulvaney, who did field questions for the remainder of the 40-minute session.

Spicer occasionally brings in an agency head to handle part of a press briefing, but he usually gives reporters some of his own time, too. At the top of a briefing last week, for example, Spicer handed off to Commerce Secretary Wilbur Ross for 21 minutes, then returned to the podium for a 26-minute Q&A.

This time, however, Spicer blew off journalists who surely would have asked the president's spokesman about the president's apparent thirst for brinkmanship.

The second part of the story is that Spicer's disappearing act on Tuesday fits into a broader trend: He has been talking to the press less and less lately.

Since Inauguration Day, Spicer has held 54 question-and-answer sessions, including formal briefings and less-formal “gaggles.” (An example of a gaggle would be a gathering of journalists around Spicer on Air Force One when the president is traveling.) I charted the duration of each session:

As you can see, there is a wide range here. That's normal.

You also can see that the peaks have been lower recently than they were earlier in the year. The decline in Spicer time becomes clearer when you break it down by month:

From January through March, Spicer's average media session lasted 45.6 minutes. In April, the average was 28.6 minutes.

The longest session in April lasted 48 minutes. That was the briefing at which Ross spoke for much of the time. None of the 14 other sessions last month even hit the average duration from the previous three months.

I noted in March that President Trump's spokesmen were spending less time answering reporters' questions than President Barack Obama's did at the same stage. Now, Spicer is falling short by his own standard.

Journalists might have been more forgiving of Spicer's cold shoulder on Tuesday if he were generous with his time, in general. But the reality is that he is becoming less and less available. The walkout was just an extreme example of his withdrawal.