A few in the list from Opensecrets.org ...

Looks like from 2011-2016 but not clear

Rank Contributor Total Indivs PACs
1 Blackstone Group $220,200 $203,700 $16,500
2 Kindred Healthcare $143,150 $113,150 $30,000
3 Humana Inc $133,300 $93,300 $40,000
4 Blue Cross/Blue Shield $122,050 $52,050 $70,000
5 Goldman Sachs $120,925 $105,925 $15,000
6 JPMorgan Chase & Co $117,075 $87,075 $30,000
7 Altria Group $113,958 $83,958 $30,000
8 DaVita HealthCare Partners $112,375 $83,375 $29,000

Opensecrests.org - Mitch McConnell

Contributions by Industry