TMZ recently reported that Saturday Night Live veteran Kenan Thompson plans to leave the iconic NBC sketch show, which he joined in 2003, at the end of the current season. SNL denied the story, but the takeaway remains the same: Kenan's been on the show for a decade? Yup: With 11 seasons under his belt, Thompson is SNL's third longest-serving cast member, after Darrell Hammond (14 seasons) and Seth Meyers (13). Since SNL premiered in 1975, 140 Not Ready for Prime Time Players have passed through Studio 8H's doors. Two, Michael Che and Pete Davidson, made their debut on the Chris Pratt-hosted 40th season premiere on Saturday. But the vast majority of these performers don't have anything close to Thompson's staying power. Many SNL careers will amount to a handful of forgettable sketch appearances. Getting the nod from Lorne Michaels only means you get a chance to prove yourself. Of the 140 total cast members in the last four decades, just 85 made it to a second season.

We found that SNL cast members* spend an average of 3.56 seasons on the show. But only half ever make it to a third season.

Getting booted from the show after 30 seconds of airtime wouldn't bode well for a performer, but neither would lingering in its margins for 30 years. We wanted to know if there's a relationship between length of time spent on the show and fame. Is there a sweet spot? If you're cast on Saturday Night Live, how long should you stick around to ensure a successful career?

To quantify fame, we turned to the the IMDBPro STARmeter, which purports to rank celebrity popularity with a proprietary algorithm based on the pages viewed by's 160 million monthly visitors. (This ever-fluctuating metric is admittedly far from perfect. In 2013, a little-known actress named Shannon Guess briefly occupied the STARmeter's top spot after making headlines for sending ricin-laced envelopes to Barack Obama and Michael Bloomberg.) By this measure, the most successful alum is Robert Downey Jr. (1985-86), with a rank of 69. The lower your STARmeter number, the more popular you are. The median rank for all SNL cast members is 6,887. We divided them accordingly, between those whose scores are lower than the median (for context, Laraine "Connie Conehead" Newman was the last to make the cut) and those has-beens and never-weres with rankings in the nosebleed section. For our purposes, we'll consider the former group—the 70 most popular SNL alumni—to be "famous," which in this case implies a generally successful post-SNL career.

With a big caveat for the many outliers who don't fit the mold, on the whole, four seasons or more on SNL appears to be the tipping point for future fame. For all those cast members who lasted three or fewer seasons on SNL, just 38.8 percent made the fame threshold. For those who lasted four seasons or more, that number jumps to 65.0 percent.

Breaking that four-year bubble—as Kate McKinnon has this season—means a formidable bump in your chances for fame. Given that Aidy Bryant and Cecily Strong have just entered their third season, we'd recommend they stay put for at least one more.

One way to achieve at least moderate celebrity status is to stay at SNL as long as they'll have you. But that doesn't mean leaving after one season is a career death sentence, either—you're just facing stiffer odds. A surprising number of SNL's most wildly famous grads defied those odds as single-seasoners, including Ben Stiller, Sarah Silverman, Billy Crystal and Robert Downey Jr. Sometimes a little goes a long way.

*Including both repertory players—that is, the main cast—and featured players. Current cast members' tenure is counted as of before last week's season premiere.