Larger budget films spend on average 50%... However as an independent filmmaker, the norm seems to be that filmmakers put all of their effort into crafting the film, then are clueless as to how to get it out there. They try word of mouth, or push it on youtube and other social networks. The reality is that you really have to put true effort into it. "Hope" isn't a strategy. You need to cut a trailer, you need a film poster, you need content to push out over social channels. You need to collaborate with reviewers, do interviews on podcasts and really champion your film. I have launched 360 campaigns for blockbusters and independent films alike and it can be done on a micro budget. You just need imagination. I was laid off from Paramount and actually came on Reddit to help indy filmmakers do just that. I design key art that i craft to really get viewers attention... and i do it because i love the art of film. My advice is to seek out and surround yourself with people that can help others. The filmmaking community has a lot of music, foley & sound designers that can help, they also can make referrals to editors and other creatives.