Final answer:
The proportion of Caucasian American offenders on parole cannot be determined based on the given information.
Step-by-step explanation:
The statement is not provided in the given information. However, the information shared indicates that the U.S. incarceration rate has grown significantly over the years, but has started declining in the past decade. It does not specifically mention about the proportion of Caucasian American offenders on parole. Therefore, without additional information, we cannot determine whether the proportion of Caucasian American offenders on parole has increased or not.