In 2006, 30 people arrested in Seattle for marijuana only

Below are two charts from the Final Report of the Marijuana Policy Review Panel on the Implementation of Initiative 75 which made the enforcement of marijuana laws the lowest priority for Seattle Police.

Table 1 shows that in 2006, there were 125 "total marijuana cases filed" by the Seattle Police Department.  Of those, 30 (24%) were "marijuana only" charges.

Table 7 shows that 0.8% of all misdemeanor filings in Seattle were for marijuana in 2006.

Here is another link to the report.