Mac Chrome users as a percentage of total users or as a percentage of Mac users? My traffic breaks down as Macs making up 7.46% total visits and Chrome is used by 7.91% of those Mac users (the percentages are oddly close, but unrelated). Safari makes up the vast majority of Mac browser share, 76.30% for me.

But it's an even smaller slice when looking at who's using 10.5. Fraction of a fraction of a fraction of users (Mac > Chrome > 10.5).