BELOW IS COMPLETE BULLSH*T:

JLo-3
Lady Gaga-7
Britney Spears-2
Kesha-2
Rihanna-5
Beyonce-8
Katy Perry-6
Carrie Underwood-10
Kelly Clarkson-9
Leona Lewis-9.5
Christina Aguilera-9.5
Keri Hilson-5 or 6

^^This list is a bunch of bullsh*t^^

Below is a list of old-school established and legendary vocalist who all aren't powerhouses but voices meant something and some their most vocally challenging songs

Celine Dion- 9.5/10 (All By Myself)
Whitney Houston- 10/10 (All The Man That I Need)
Mariah Carey- 9.94/10 (Anytime You Need a Friend)
Pat Benatar-8.4/10 (All Fired Up)
Madonna- 6.0/10 (Like A Prayer)
Cher-8.0/10 (Living In a House Divided)
Janet Jackson-6.6/10 (Black Cat)
Mary J. Blige-7.2/10 (Love I Never Had)
Aretha Franklin-9.5/10 (You Make Me Feel Like a Natural Woman)
Tina Turner- 9.1/10 (The Best)
Natalie Cole-7.9/10 (This Will Be)
Diana Ross-7.1/10 (Sweetest Hangover)
Chaka Khan-8.8/10 (Im Every Woman)
Donna Summers-8.1/10 (Radio)
Patti LaBelle-9.0/10 (When You've Been Blessed)
Teena Marie-8.8/10 (Cassanove Brown)
Reba McEntire-7.8/10 (Whoever's in New England)
Annie Lennox-7.3/10 (Little Bird)
Deniece Williams-8.0/10 (Black Butterfly)
Barbra Streisand-8.5/10 (Evergreen)