High/low % to get pregnant

I have a question.. I’m new to this app and have been just messing around on it. I started like 2-3weeks ago and logged in my stuff from last month and when I started it said I had 3% chance of pregnancy. Just started my period today, and have been clicking on the other days (after my period) and the highest the percentage goes is 33% on my ovulation day. Is it supposed to go to 100%? I’m confused and just trying to find out the day I’m the highest likely to conceive!