This is what Gartner says is #3, and I would consider them fairly reputable as a source. Once you get past the big two, it also probably depends what you consi

This is what Gartner says is #3, and I would consider them fairly reputable as a source. Once you get past the big two, it also probably depends what you consider part of their market share. Like some include Office suites and some don't, so it probably gets less accurate.