within its first month on air, "spongebob squarepants" overtook "pokémon" as the highest rated saturday-morning children's series on television. it held an average national nielsen rating of 4.9 among children aged two through eleven, denoting 1.9 million viewers. two years later, the series had firmly established itself as nickelodeon's second highest-rated children's program, after "rugrats". "spongebob squarepants" was credited with helping nickelodeon take the "saturday-morning ratings crown" for the fourth straight season in 2001. the series had gained a significant adult audience by that point—nearly 40 percent of its 2.2 million viewers were aged 18 to 34. in response to its weekend success, nickelodeon gave "spongebob squarepants" time slots at 6:00 pm and 8:00 pm, monday through thursday, to increase the series' exposure. by the end of 2001, "spongebob squarepants" boasted the highest ratings for any children's series, on all of television. weekly viewership of the series had reached around fifteen million, at least five million of whom were adults.