The digital marketing channel specifically represents the majority of that marketing spend, at 57.1%. According to that same report, investment in digital marketing is expected to grow by a whopping 16.2% over the next year. Also, consider how much money you're spending on paid advertising. For example, a national brand that runs PPC campaigns to attract new customers should spend approximately 25% more on organic SEO.
The two channels complement each other to help boost website traffic. However, if your competition is tough, your site isn't optimized at all, and you don't have employees dedicated to marketing, you should expect to spend much more, at least initially, on SEO. For example, a company that receives thousands of searches for its services per month will have to spend more on SEO packages, while companies that provide services in an area where many similar companies will have to spend more to surpass others. Another report (The State of Marketing Budget and Strategy 202, by Garner) reported that more than half of all digital spending goes to paid channels, but that at least 8.5% continues to go to SEO spending.
What you pay for SEO will depend on the size of your company, as smaller companies spend less than large ones, which is often tailored to an organization's SEO needs.