I've tracked my time for over 2 years solid.

The first year (2007) I was 46% billable efficiency (web design).

The second year (2008) I was 49% billable efficiency (doing web design).

I also do sales / marketing / customer service / and building my own web app so this is purely consulting stuff with clients and I'm happy with the numbers.

In 2007 I worked 2784 hours. In 2008 I worked about 600 hours less than the previous year. I think that was my goal going into the year. Objective achieved!