Here is a breakdown of the top rated channels (saving the search):
(Organic Search) 28% Excellent
Email Marketing 26% Excellent
Paid Search (PPC) 15% Excellent
Social Media 11% Excellent
Mobile Marketing 8% Excellent
Affiliate Marketing 8% Excellent
Offline Direct Marketing 6% Excellent
Online Display Ads 2 % Excellent
From what I've seen insurance marketers do better than average with mobile paid search bid adjustments because most consumers would rather speak with an agent who can enroll them by phone rather than try to compare, shop and enroll through the tiny mobile viewport.
Here is another marketing channel allocation report, I like how this one breaks out email for acquisition (w/o optin) & for engagement & retention (w/ opt-in)
The marketing channel source is typically allocated to the last in marketing channel, though beginning or middle sources are often given some weight.
If you have Google Analytics set up you can see a channel contribution by following this path:
Acquistion - All Traffic - Channels