From Holden:

I’m sure this can be easily explained.

Tennessee Sen. Bill Frist has been ferried on corporate aircraft more than most other politicians in Washington over the past five years, according to a study released this week.

[snip]

Frist’s most frequent corporate hosts were pharmaceutical companies, including Abbott Laboratories, Pfizer Corp. and Schering-Plough. He reimbursed the three $22,656 for use of their aircraft, the report states.