I’m having a lot of trouble understanding your question. When you say that you are older than a lot of people in your “year,” are you referring to the number of units they have accumulated (which often determines freshman, sophomore, junior, etc, standing) or are you referring to the actual year they are in college (i.e. they’re first year or second year, etc)?
Either way, I don’t think I really understand what your question is, but maybe I’m just being really dense. It has nothing to do with graduation rates.
If by “year” you mean their year in college, like first year, second year, etc, then you’ll always be older than the kids in your “grade.” You started older than most of the kids in your grade, so in your sophomore year, you’re still going to be older than most of the kids in your grade. Those same students are going to keep moving up in their year at college along with you, so you’re always going to be older than most of the kids in your grade. You may graduate in four years, while they’re still trucking along into their fifth or sixth year, but that doesn’t affect whether they are in your year currently.
If by “year” you mean the number of units they have (if they technically have freshman, sophomore, junior, senior standing), then your reasoning only works in all of the students who take longer than four years to graduate are doing so because they are taking a substantially smaller number of units than you are. Many students don’t graduate on time because they switched majors a lot or are double majoring or are taking the minimum units to meet satisfactory academic progress. They may likely still be advancing in terms of their freshmen to sophomore to junior to senior standing but aren’t fulfilling all of the requirements they need to graduate in their intended major so they need an extra year to graduate. Or they switch majors later on and need to take longer to fulfill all of the requirements. They’re still sophomore standing with you, but this has no effect on their age so they’ll still generally be younger than you.
Also, how are you determining who’s in your year and who’s not? When I was in college, I had no idea what year someone was in unless I asked them. Are you asking everyone what year they’re in and how old they are?
Perhaps, I’m really missing something, but I just don’t understand how graduation rates have anything to do with the age of your classmates in your year.