Participation percentage is the percent of available entries a member has earned so far in a calendar month. Each day there are 16 new entries available.
Participation percentage is a moving target. This is especially obvious at the beginning of the month. Yesterday being the first day in the month, the max potential available entries were 16. When you woke up this morning the max potential was 32, and when you wake tomorrow it will be 48 etc...
You earn entries as you go through your day, yesterday you had X out of 16, at the beginning of the day today you probably still had X but now it was out of 32. As you log throughout the day your X will become Y out of 32 but tomorrow morning until you start logging again it will still be Y only out of 48 this time and that will continue to grow daily.
Participation is meant to be consumed in arears, but your number will get clearer as you get closer to the end of a month.