Thousands. Once upon a time, the telecommunications companies who ran/run the internet had more open peering policies and it was possible to have a Mom & Pop ISP that connected to the major exchanges. They could offer web hosting and colocation (your machine, their racks) as additional services and people could have a nice little business.
Then the big boys started excluding smaller providers, starving them like a gazelle with a broken leg until the hyenas of Larger Business swept them up. To be sure, there was also plain, MBA-style consolidation, but restricting peering prevented new independent providers from replacing them (yet another instance of Boomers pulling up the ladder after themselves).