I almost always had a part time job during college and I think most people I knew worked in college as well. I remember one guy in the dorms who didn't work at all and his parents were paying for his college and giving him an allowance of some sort. At least one other guy was an athlete on scholarship and he didn't have a job. In fact I'm not even sure scholarship athletes are allowed to have jobs while on campus but thats beside the point. One guy had a part time type job as a street musician of all things. I don't think his roommate worked. But overall most people I recall seemed to work.
I found data at the Dept. of Education in their Digest of Education Statistics :
Table 503.20. Percentage of college students 16 to 24 years old who were employed, by attendance status, hours worked per week, and control and level of institution: Selected years, October 1970 through 2012
As of 2012 : 41% of full time students are employed and 72% of part time students work.
The rates are very similar for 4 year public, 4 year private and 2 year public schools as follows :
|4 year public||41.0%||77.6%|
|4 year private||40.4%||84.4%|
|2 year public||41.2%||66.1%|
Here's the history over time for all students :
As you can see in the past 10 years theres been a fair drop in the % of students working. I'm guessing thats a result of the recent recession and the employment environment, but thats just me speculating.