This is actually a very difficult question to answer, and one that is being actively studied. Made even more difficult is that there is a considerable variability in the day-to-day for some of these gasses, and particularly year round.
Carbon Dioxide will freeze at certain times of the year. This is a chart of Viking 1's pressure over a season, this is primarily due to the CO2 freezing.
Oxygen is a much more challenging gas. There has been some measurement of the variability of O2. The pattern doesn't quite fit what is predicted in the mold.
I haven't seen anything directly about CO. Argon and Nitrogen are pretty stable long term.
All that being said, there are some losses of all of these gas. All of the gasses are being lost to some extent, although the amount is pretty small, and they seem fairly stable. Wikipedia does a good job of explaining all of the various ways that gases can be lost.