Final answer:
The exact fraction of college students who do not re-enroll due to drinking is not provided. College retention rates are influenced by multiple factors, including possibly alcohol use, but specific data on drinking as the cause of dropout is needed for a precise figure.
Step-by-step explanation:
The specific fraction of college students who fail to enroll in their second year due to drinking is not immediately provided in the information given. However, it is important to note that health and lifestyle choices, including drinking, can significantly affect academic performance and college retention rates. First-generation college students, for example, tend to have lower graduation rates. In the context provided, 89 percent of such students do not earn a degree within six years, which implies they are dropping out at relatively high rates. This may be influenced by a variety of factors, including potentially alcohol use, though the specific impact of drinking on these statistics would require more detailed research data which is not included in the provided information.