Artist with year-end hits that span at least 5 years and...

[plankton5165]

In their first year, they were less than 20 years old. (I could not fit this in the title)

A few examples: An artist that first took a song to the year-end in 2015 must have also done so in 2020 or later. In 2015, that singer would have to be less than 20 years old, but not in 2020 or later. So, if they were 22 in 2020, that would mean they were 17 in 2015, and thus eligible for being listed here.

By the way, songs that a singer did as part of a band before eventually going solo count will count towards the span of the solo act.

18 years:
Rihanna (b. 1988) (2005-2023)
16 years:
Taylor Swift (b. 1989) (2007-2023)
14 years:
Britney Spears (b. 1981) (1999-2013)
13 years:
Justin Bieber (b. 1994) (2009-2022)
9 years:
Aaliyah (1979-2001) (1994-2003)
Avril Lavigne (b. 1984) (2002-2011)

[avamaxstan]

Immediately looked for the prime example in the OP and it was missing.

Britney Spears
1999 (Baby One More Time)
2004 (Toxic)
2008 (Piece of Me, Womanizer)
2009 (Womanizer, Circus, If U Seek Amy, 3)
2010 (3)
2011 (Till the World Ends, I Wanna Go, Hold It Against Me)
2013 (Scream & Shout)

Also... Avril in 2002 (Complicated, Sk8er Boi) and 2007 (Girlfriend, Keep Holding On)

And Rihanna... 2005-2010 and almost every year the rest of the decade. 

I feel like there are too many examples for the entire year-end top 100. Top 25 would be a more exclusive list.

[renfield75]

Michael Jackson was 11 when the Jackson 5 first hit number one in 1970. Even without the Jackson 5 he was still 13 when he hit number 4 solo with "Rockin' Robin" in 1972.

Brandy made the 1995 year end when she was 16 and had hits in 2002's year-end.

As part of Destiny's Child Beyonce was 16 when "No No No" was released in 1997.

Christina Aguilera was a teenager when she made the 1999 year-end and she made it again in the 2010s with "Moves Like Jagger" and "Say Something".

Billie Eilish was 17 when "Bad Guy" was released in 2019. There's a good chance she makes the 2024 year-end 5 years later.

Justin Timberlake with NSYNC, Harry Styles with One Direction...Jordan Knight & Joey McIntyre from New Kids On The Block were teens when they made the 1989 year-end and both made the year-end in 1999 as solo artists.

[WolfSpear]

What’s the longest span of YE top 10 hits? Elton?

[G@bing$20n]

Selena Gomez, 2010 (Naturally) to 2023 (Calm Down).

[Baby Yoda Hot100Fan]

34 years: Cher (b. 1946) (1965-1999)

Elton John doesn't qualify because he was already 25 years old (b. 1947) when he made his first Year-End Hot 100 in 1972.

[jdanton2]

if we were to count Christmas songs Brenda Lee who was born in 1944 had her first year end chart single in 1960 and in 2023 hit the year end chart with Rockin' Around the Christmas Tree.

[wyckyd]

Donny Osmond (b. 1957), from 1971 to 1989
Stevie Wonder (b. 1950), from 1963 to 1986