What are the main reasons and sources of the increased CO2 levels?

How have levels of carbon dioxide in the atmosphere changed in the past 100 years? Give specific quantities from Pre-Industrial Revolution compared to now.

The main sources are humans which is why it is stated that the global warming is man made. The levels have increased beyond all measure, increasing since the 1950s by a 100 CO2 parts per million, and it keeps increasing by 2ppm on a yearly basis. The statistics from the industrial revolution era are not much different and show how much we've increased the CO2 in modern times.