Lead (in sales) over the #2 in 2016 according to Kworb estimations:
January 7th - 52K (Justin Bieber - Love Yourself)
January 14th - 31K (Justin Bieber - Love Yourself)
January 21th - 16K (Justin Bieber - Love Yourself)
January 28th - 7K (Rihanna f/ Drake - Work)
February 4th - 45K (ZAYN - PILLOWTALK)
February 11th - 31K (Flo Rida - My House)
February 18th - 24K (Flo Rida - My House)
February 25th - 54K (Rihanna f/ Drake - Work)
March 3rd - 37K (Kelly Clarkson - Piece By Piece)
March 10th - 9K (Lukas Graham - 7 Years)
March 17th - 29K (Lukas Graham - 7 Years)
March 24th - 4K (Meghan Trainor - NO)
March 31st - 1K (Lukas Graham - 7 Years)
April 7th - 8K (Lukas Graham - 7 Years)
April 14th - 27K (Drake f/ Kyla, Wizkid - One Dance)
April 21st - 0K (Prince - Purple Rain)
April 28th - 75K (Prince - Purple Rain)
May 5th - 48K (Drake f/ Kyla, Wizkid - One Dance)
May 12th - 218K (Justin Timberlake - Cant Stop The Feeling)
May 19th - 74K (Justin Timberlake - Cant Stop The Feeling)
May 26th - 57K (Justin Timberlake - Cant Stop The Feeling)
June 2nd - 52K (Justin Timberlake - Cant Stop The Feeling)
June 9th - 45K (Justin Timberlake - Cant Stop The Feeling)
June 16th - 36K (Justin Timberlake - Cant Stop The Feeling)
June 23rd - 33K (Justin Timberlake - Cant Stop The Feeling)
June 30th - 23K (Justin Timberlake - Cant Stop The Feeling)
July 7th - 15K (Justin Timberlake - Cant Stop The Feeling)
July 14th - 2K (Justin Timberlake - Cant Stop The Feeling)
July 21st - 18K (Katy Perry - Rise)
July 28th - 40K (Major Lazer f/ Justin Bieber, MO)
August 4th - 10K (The Chainsmokers f/ Halsey - Closer)
August 11th - 15K (DJ Snake f/ Justin Bieber - Let Me Love You)
August 18th - 37K (The Chainsmokers f/ Halsey - Closer)
August 25th - 66K (The Chainsmokers f/ Halsey - Closer)
September 1st - 128K (The Chainsmokers f/ Halsey - Closer)
September 8th - 118K (The Chainsmokers f/ Halsey - Closer)
September 15th - 73K (The Chainsmokers f/ Halsey - Closer)
September 22nd - 72K (The Chainsmokers f/ Halsey - Closer)
September 29th - 43K (The Chainsmokers f/ Halsey - Closer)
October 6th - 30K (The Chainsmokers f/ Halsey - Closer)
October 6th - 30K (The Chainsmokers f/ Halsey - Closer)
October 13th - 12K (The Chainsmokers f/ Halsey - Closer)
October 20th - 9K (The Chainsmokers f/ Halsey - Closer)
October 27th - 11K (The Chainsmokers f/ Halsey - Closer)
November 3rd - 3K (The Chainsmokers f/ Halsey - Closer)
November 10th - 76K (Rae Sremmurd f/ Gucci Mane)
November 17th - 78K (Rae Sremmurd f/ Gucci Mane)
November 24th - 42K (Rae Sremmurd f/ Gucci Mane)
December 1st - 4K (Rae Sremmurd f/ Gucci Mane)
December 8th - 3K (Rae Sremmurd f/ Gucci Mane)
December 15th - 120K (ZAYN & Taylor Swift - I Don't Wanna Live Forever)
If this prediction ends up being accurate, it'd be the 4th time this year where the #1 has a 100K lead over the #2