sakuracon http://www.sakuracon.org/ This convention is 5 times the size of Kumoricon.
If you look year by year, we're doing pretty good
Sakura Year 1, 313 people
Sakura year 2, 553 people
Sakura Year 3, 866 people
Sakura Year 4, 1519 people
Sakura Year 5, 2328 people
Kumoricon Year 1, aprox 500 people (in a town of 1/4 million rather than Seattle sized!
Kumoricon Year 2, we will have a prereg total of about 500, and expect the total number of attendees to be between 800 and 1200 people.
I'd say we are very much on track to becoming a second major convention in the area! Many of us are involved in both and kind of consider ourselves "sister conventions" even though no official agreement exists.