1.   Still, these averages mask a lot of protectionism for individual sectors.

2.   Averages can mask fluctuations, but this year the market has been very consistent.

3.   But such averages mask the fact that a few participants were far more successful while others failed to earn extra money.

4.   But those averages mask wildly divergent clinic-to-clinic differences.

5.   However, that average masks a considerable range.

6.   The average masks some harsh realities, however.