It looks to me like fossil fuels contribute have contributed about 160% of the increase in CO2 in the atmosphere:

Using 1ppm in the atmosphere of CO2 weighing about 7.82 GT, the increase from pre-industrial CO2 of about 140ppm would be about 1095 GT of CO2.

Using the our world in data data, cumulative emissions from fossil fuels alone are 1770 GT of CO2