Government sources are preferred. Although they are frequently based on private reports, they provide some consistency. However, many government reports in recent years offered inconsistent units of measurement and discontinued annual market updates. Readers should use caution in interpreting data for individual years and instead emphasize the trends over several years. One limitation of this government data is the lag time before statistics are reported, with the most recent data being a year or more old. The companion website for this book (www.tfi.com/ctu) reports more detailed statistics than could be printed in this chapter.