What percentage of local main-sequence stars are accounted for when combining M and K dwarfs?

Well over 80%

When assessing the numerical distribution of main-sequence stars in the local galactic disk, the two most populous cool spectral classes—M-type (Red Dwarfs) and K-type (Orange Dwarfs)—collectively dominate the stellar count. The Red Dwarfs contribute approximately 70% to 76%, while the Orange Dwarfs add another significant fraction, constituting about 12% to 15% of the total population. Summing these two groups results in a combined figure that surpasses the 80% threshold, indicating that the vast majority of stars currently undergoing core hydrogen fusion in our neighborhood belong to these cool, dim categories. This massive numerical contribution underscores why focusing only on bright stars yields an incomplete picture of the galaxy's structure.