Here a party receiving money from companies is a big deal.
The majority of political donations come from individuals.
Obama for example raised $1.23 billion from individual contributions over his political career. Out of about $1.5 billion total.
For Trump, about 60% of his campaign's funding came from individual donations (about $220m), his money included. Trump gave about $66m to his own campaign, or around 20% of all the funding. Supporting PACs spent around $100 million.
Hillary Clinton got about 71% of her campaign funds from individual contributions (around $405m). Her supporting PACs spent around $210m.
For the prominent Ted Cruz vs Beto O'Rourke Texas Senate battle, Cruz got 77% of his funding from individual contributions.
From there you'd have to look into the share of the PAC money that comes from individuals versus companies etc. PACs commonly derive a large share of their funding from individual contributions. For some of that you can get good figures, some of it is shadowy.